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rfc:rfc5804

Internet Engineering Task Force (IETF) A. Melnikov, Ed. Request for Comments: 5804 Isode Limited Category: Standards Track T. Martin ISSN: 2070-1721 BeThereBeSquare, Inc.

                                                             July 2010
            A Protocol for Remotely Managing Sieve Scripts

Abstract

 Sieve scripts allow users to filter incoming email.  Message stores
 are commonly sealed servers so users cannot log into them, yet users
 must be able to update their scripts on them.  This document
 describes a protocol "ManageSieve" for securely managing Sieve
 scripts on a remote server.  This protocol allows a user to have
 multiple scripts, and also alerts a user to syntactically flawed
 scripts.

Status of This Memo

 This is an Internet Standards Track document.
 This document is a product of the Internet Engineering Task Force
 (IETF).  It represents the consensus of the IETF community.  It has
 received public review and has been approved for publication by the
 Internet Engineering Steering Group (IESG).  Further information on
 Internet Standards is available in Section 2 of RFC 5741.
 Information about the current status of this document, any errata,
 and how to provide feedback on it may be obtained at
 http://www.rfc-editor.org/info/rfc5804.

Copyright Notice

 Copyright (c) 2010 IETF Trust and the persons identified as the
 document authors.  All rights reserved.
 This document is subject to BCP 78 and the IETF Trust's Legal
 Provisions Relating to IETF Documents
 (http://trustee.ietf.org/license-info) in effect on the date of
 publication of this document.  Please review these documents
 carefully, as they describe your rights and restrictions with respect
 to this document.  Code Components extracted from this document must
 include Simplified BSD License text as described in Section 4.e of
 the Trust Legal Provisions and are provided without warranty as
 described in the Simplified BSD License.

Melnikov & Martin Standards Track [Page 1] RFC 5804 ManageSieve July 2010

Table of Contents

 1. Introduction ....................................................3
    1.1. Commands and Responses .....................................3
    1.2. Syntax .....................................................3
    1.3. Response Codes .............................................3
    1.4. Active Script ..............................................6
    1.5. Quotas .....................................................6
    1.6. Script Names ...............................................6
    1.7. Capabilities ...............................................7
    1.8. Transport ..................................................9
    1.9. Conventions Used in This Document .........................10
 2. Commands .......................................................10
    2.1. AUTHENTICATE Command ......................................11
         2.1.1. Use of SASL PLAIN Mechanism over TLS ...............16
    2.2. STARTTLS Command ..........................................16
         2.2.1. Server Identity Check ..............................17
    2.3. LOGOUT Command ............................................20
    2.4. CAPABILITY Command ........................................20
    2.5. HAVESPACE Command .........................................20
    2.6. PUTSCRIPT Command .........................................21
    2.7. LISTSCRIPTS Command .......................................23
    2.8. SETACTIVE Command .........................................24
    2.9. GETSCRIPT Command .........................................25
    2.10. DELETESCRIPT Command .....................................25
    2.11. RENAMESCRIPT Command .....................................26
    2.12. CHECKSCRIPT Command ......................................27
    2.13. NOOP Command .............................................28
    2.14. Recommended Extensions ...................................28
         2.14.1. UNAUTHENTICATE Command ............................28
 3. Sieve URL Scheme ...............................................29
 4. Formal Syntax ..................................................31
 5. Security Considerations ........................................37
 6. IANA Considerations ............................................38
    6.1. ManageSieve Capability Registration Template ..............39
    6.2. Registration of Initial ManageSieve Capabilities ..........39
    6.3. ManageSieve Response Code Registration Template ...........41
    6.4. Registration of Initial ManageSieve Response Codes ........41
 7. Internationalization Considerations ............................46
 8. Acknowledgements ...............................................46
 9. References .....................................................47
    9.1. Normative References ......................................47
    9.2. Informative References ....................................48

Melnikov & Martin Standards Track [Page 2] RFC 5804 ManageSieve July 2010

1. Introduction

1.1. Commands and Responses

 A ManageSieve connection consists of the establishment of a client/
 server network connection, an initial greeting from the server, and
 client/server interactions.  These client/server interactions consist
 of a client command, server data, and a server completion result
 response.
 All interactions transmitted by client and server are in the form of
 lines, that is, strings that end with a CRLF.  The protocol receiver
 of a ManageSieve client or server is either reading a line or reading
 a sequence of octets with a known count followed by a line.

1.2. Syntax

 ManageSieve is a line-oriented protocol much like [IMAP] or [ACAP],
 which runs over TCP.  There are three data types: atoms, numbers and
 strings.  Strings may be quoted or literal.  See [ACAP] for detailed
 descriptions of these types.
 Each command consists of an atom (the command name) followed by zero
 or more strings and numbers terminated by CRLF.
 All client queries are replied to with either an OK, NO, or BYE
 response.  Each response may be followed by a response code (see
 Section 1.3) and by a string consisting of human-readable text in the
 local language (as returned by the LANGUAGE capability; see
 Section 1.7), encoded in UTF-8 [UTF-8].  The contents of the string
 SHOULD be shown to the user ,and implementations MUST NOT attempt to
 parse the message for meaning.
 The BYE response SHOULD be used if the server wishes to close the
 connection.  A server may wish to do this because the client was idle
 for too long or there were too many failed authentication attempts.
 This response can be issued at any time and should be immediately
 followed by a server hang-up of the connection.  If a server has an
 inactivity timeout resulting in client autologout, it MUST be no less
 than 30 minutes after successful authentication.  The inactivity
 timeout MAY be less before authentication.

1.3. Response Codes

 An OK, NO, or BYE response from the server MAY contain a response
 code to describe the event in a more detailed machine-parsable
 fashion.  A response code consists of data inside parentheses in the
 form of an atom, possibly followed by a space and arguments.

Melnikov & Martin Standards Track [Page 3] RFC 5804 ManageSieve July 2010

 Response codes are defined when there is a specific action that a
 client can take based upon the additional information.  In order to
 support future extension, the response code is represented as a
 slash-separated (Solidus, %x2F) hierarchy with each level of
 hierarchy representing increasing detail about the error.  Response
 codes MUST NOT start with the Solidus character.  Clients MUST
 tolerate additional hierarchical response code detail that they don't
 understand.  For example, if the client supports the "QUOTA" response
 code, but doesn't understand the "QUOTA/MAXSCRIPTS" response code, it
 should treat "QUOTA/MAXSCRIPTS" as "QUOTA".
 Client implementations MUST tolerate (ignore) response codes that
 they do not recognize.
 The currently defined response codes are the following:
 AUTH-TOO-WEAK
 This response code is returned in the NO or BYE response from an
 AUTHENTICATE command.  It indicates that site security policy forbids
 the use of the requested mechanism for the specified authentication
 identity.
 ENCRYPT-NEEDED
 This response code is returned in the NO or BYE response from an
 AUTHENTICATE command.  It indicates that site security policy
 requires the use of a strong encryption mechanism for the specified
 authentication identity and mechanism.
 QUOTA
 If this response code is returned in the NO/BYE response, it means
 that the command would have placed the user above the site-defined
 quota constraints.  If this response code is returned in the OK
 response, it can mean that the user's storage is near its quota, or
 it can mean that the account exceeded its quota but that the
 condition is being allowed by the server (the server supports
 so-called soft quotas).  The QUOTA response code has two more
 detailed variants: "QUOTA/MAXSCRIPTS" (the maximum number of per-user
 scripts) and "QUOTA/MAXSIZE" (the maximum script size).
 REFERRAL
 This response code may be returned with a BYE result from any
 command, and includes a mandatory parameter that indicates what
 server to access to manage this user's Sieve scripts.  The server
 will be specified by a Sieve URL (see Section 3).  The scriptname

Melnikov & Martin Standards Track [Page 4] RFC 5804 ManageSieve July 2010

 portion of the URL MUST NOT be specified.  The client should
 authenticate to the specified server and use it for all further
 commands in the current session.
 SASL
 This response code can occur in the OK response to a successful
 AUTHENTICATE command and includes the optional final server response
 data from the server as specified by [SASL].
 TRANSITION-NEEDED
 This response code occurs in a NO response of an AUTHENTICATE
 command.  It indicates that the user name is valid, but the entry in
 the authentication database needs to be updated in order to permit
 authentication with the specified mechanism.  This is typically done
 by establishing a secure channel using TLS, verifying server identity
 as specified in Section 2.2.1, and finally authenticating once using
 the [PLAIN] authentication mechanism.  The selected mechanism SHOULD
 then work for authentications in subsequent sessions.
 This condition can happen if a user has an entry in a system
 authentication database such as Unix /etc/passwd, but does not have
 credentials suitable for use by the specified mechanism.
 TRYLATER
 A command failed due to a temporary server failure.  The client MAY
 continue using local information and try the command later.  This
 response code only makes sense when returned in a NO/BYE response.
 ACTIVE
 A command failed because it is not allowed on the active script, for
 example, DELETESCRIPT on the active script.  This response code only
 makes sense when returned in a NO/BYE response.
 NONEXISTENT
 A command failed because the referenced script name doesn't exist.
 This response code only makes sense when returned in a NO/BYE
 response.
 ALREADYEXISTS
 A command failed because the referenced script name already exists.
 This response code only makes sense when returned in a NO/BYE
 response.

Melnikov & Martin Standards Track [Page 5] RFC 5804 ManageSieve July 2010

 TAG
 This response code name is followed by a string specified in the
 command.  See Section 2.13 for a possible use case.
 WARNINGS
 This response code MAY be returned by the server in the OK response
 (but it might be returned with the NO/BYE response as well) and
 signals the client that even though the script is syntactically
 valid, it might contain errors not intended by the script writer.
 This response code is typically returned in response to PUTSCRIPT
 and/or CHECKSCRIPT commands.  A client seeing such response code
 SHOULD present the returned warning text to the user.

1.4. Active Script

 A user may have multiple Sieve scripts on the server, yet only one
 script may be used for filtering of incoming messages.  This is the
 active script.  Users may have zero or one active script and MUST use
 the SETACTIVE command described below for changing the active script
 or disabling Sieve processing.  For example, users may have an
 everyday script they normally use and a special script they use when
 they go on vacation.  Users can change which script is being used
 without having to download and upload a script stored somewhere else.

1.5. Quotas

 Servers SHOULD impose quotas to prevent malicious users from
 overflowing available storage.  If a command would place a user over
 a quota setting, servers that impose such quotas MUST reply with a NO
 response containing the QUOTA response code.  Client implementations
 MUST be able to handle commands failing because of quota
 restrictions.

1.6. Script Names

 A Sieve script name is a sequence of Unicode characters encoded in
 UTF-8 [UTF-8].  A script name MUST comply with Net-Unicode Definition
 (Section 2 of [NET-UNICODE]), with the additional restriction of
 prohibiting the following Unicode characters:
 o  0000-001F; [CONTROL CHARACTERS]
 o  007F; DELETE
 o  0080-009F; [CONTROL CHARACTERS]

Melnikov & Martin Standards Track [Page 6] RFC 5804 ManageSieve July 2010

 o  2028; LINE SEPARATOR
 o  2029; PARAGRAPH SEPARATOR
 Sieve script names MUST be at least one octet (and hence Unicode
 character) long.  Zero octets script name has a special meaning (see
 Section 2.8).  Servers MUST allow names of up to 128 Unicode
 characters in length (which can take up to 512 bytes when encoded in
 UTF-8, not counting the terminating NUL), and MAY allow longer names.
 A server that receives a script name longer than its internal limit
 MUST reject the corresponding operation, in particular it MUST NOT
 truncate the script name.

1.7. Capabilities

 Server capabilities are sent automatically by the server upon a
 client connection, or after successful STARTTLS and AUTHENTICATE
 (which establishes a Simple Authentication and Security Layer (SASL))
 commands.  Capabilities may change immediately after a successfully
 completed STARTTLS command, and/or immediately after a successfully
 completed AUTHENTICATE command, and/or after a successfully completed
 UNAUTHENTICATE command (see Section 2.14.1).  Capabilities MUST
 remain static at all other times.
 Clients MAY request the capabilities at a later time by issuing the
 CAPABILITY command described later.  The capabilities consist of a
 series of lines each with one or two strings.  The first string is
 the name of the capability, which is case-insensitive.  The second
 optional string is the value associated with that capability.  Order
 of capabilities is arbitrary, but each capability name can appear at
 most once.
 The following capabilities are defined in this document:
 IMPLEMENTATION - Name of implementation and version.  This capability
 MUST always be returned by the server.
 SASL - List of SASL mechanisms supported by the server, each
 separated by a space.  This list can be empty if and only if STARTTLS
 is also advertised.  This means that the client must negotiate TLS
 encryption with STARTTLS first, at which point the SASL capability
 will list a non-empty list of SASL mechanisms.
 SIEVE - List of space-separated Sieve extensions (as listed in Sieve
 "require" action [SIEVE]) supported by the Sieve engine.  This
 capability MUST always be returned by the server.

Melnikov & Martin Standards Track [Page 7] RFC 5804 ManageSieve July 2010

 STARTTLS - If TLS [TLS] is supported by this implementation.  Before
 advertising this capability a server MUST verify to the best of its
 ability that TLS can be successfully negotiated by a client with
 common cipher suites.  Specifically, a server should verify that a
 server certificate has been installed and that the TLS subsystem has
 successfully initialized.  This capability SHOULD NOT be advertised
 once STARTTLS or AUTHENTICATE command completes successfully.  Client
 and server implementations MUST implement the STARTTLS extension.
 MAXREDIRECTS - Specifies the limit on the number of Sieve "redirect"
 actions a script can perform during a single evaluation.  Note that
 this is different from the total number of "redirect" actions a
 script can contain.  The value is a non-negative number represented
 as a ManageSieve string.
 NOTIFY - A space-separated list of URI schema parts for supported
 notification methods.  This capability MUST be specified if the Sieve
 implementation supports the "enotify" extension [NOTIFY].
 LANGUAGE - The language (<Language-Tag> from [RFC5646]) currently
 used for human-readable error messages.  If this capability is not
 returned, the "i-default" [RFC2277] language is assumed.  Note that
 the current language MAY be per-user configurable (i.e., it MAY
 change after authentication).
 OWNER - The canonical name of the logged-in user (SASL "authorization
 identity") encoded in UTF-8.  This capability MUST NOT be returned in
 unauthenticated state and SHOULD be returned once the AUTHENTICATE
 command succeeds.
 VERSION - This capability MUST be returned by servers compliant with
 this document or its successor.  For servers compliant with this
 document, the capability value is the string "1.0".  Lack of this
 capability means that the server predates this specification and thus
 doesn't support the following commands: RENAMESCRIPT, CHECKSCRIPT,
 and NOOP.
 Section 2.14 defines some additional ManageSieve extensions and their
 respective capabilities.
 A server implementation MUST return SIEVE, IMPLEMENTATION, and
 VERSION capabilities.
 A client implementation MUST ignore any listed capabilities that it
 does not understand.

Melnikov & Martin Standards Track [Page 8] RFC 5804 ManageSieve July 2010

     Example:
     S: "IMPlemENTATION" "Example1 ManageSieved v001"
     S: "SASl" "DIGEST-MD5 GSSAPI"
     S: "SIeVE" "fileinto vacation"
     S: "StaRTTLS"
     S: "NOTIFY" "xmpp mailto"
     S: "MAXREdIRECTS" "5"
     S: "VERSION" "1.0"
     S: OK
 After successful authentication, this might look like this:
     Example:
     S: "IMPlemENTATION" "Example1 ManageSieved v001"
     S: "SASl" "DIGEST-MD5 GSSAPI"
     S: "SIeVE" "fileinto vacation"
     S: "NOTIFY" "xmpp mailto"
     S: "OWNER" "alexey@example.com"
     S: "MAXREdIRECTS" "5"
     S: "VERSION" "1.0"
     S: OK

1.8. Transport

 The ManageSieve protocol assumes a reliable data stream such as that
 provided by TCP.  When TCP is used, a ManageSieve server typically
 listens on port 4190.
 Before opening the TCP connection, the ManageSieve client first MUST
 resolve the Domain Name System (DNS) hostname associated with the
 receiving entity and determine the appropriate TCP port for
 communication with the receiving entity.  The process is as follows:
 1.  Attempt to resolve the hostname using a [DNS-SRV] Service of
     "sieve" and a Proto of "tcp" for the target domain (e.g.,
     "example.net"), resulting in resource records such as
     "_sieve._tcp.example.net.".  The result of the SRV lookup, if
     successful, will be one or more combinations of a port and
     hostname; the ManageSieve client MUST resolve the returned
     hostnames to IPv4/IPv6 addresses according to returned SRV record
     weight.  IP addresses from the first successfully resolved
     hostname (with the corresponding port number returned by SRV
     lookup) are used to connect to the server.  If connection using
     one of the IP addresses fails, the next resolved IP address is

Melnikov & Martin Standards Track [Page 9] RFC 5804 ManageSieve July 2010

     used to connect.  If connection to all resolved IP addresses
     fails, then the resolution/connect is repeated for the next
     hostname returned by SRV lookup.
 2.  If the SRV lookup fails, the fallback SHOULD be a normal IPv4 or
     IPv6 address record resolution to determine the IP address, where
     the port used is the default ManageSieve port of 4190.

1.9. Conventions Used in This Document

 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
 document are to be interpreted as described in [KEYWORDS].
 In examples, "C:" and "S:" indicate lines sent by the client and
 server respectively.  Line breaks that do not start a new "C:" or
 "S:" exist for editorial reasons.
 Examples of authentication in this document are using DIGEST-MD5
 [DIGEST-MD5] and GSSAPI [GSSAPI] SASL mechanisms.

2. Commands

 This section and its subsections describe valid ManageSieve commands.
 Upon initial connection to the server, the client's session is in
 non-authenticated state.  Prior to successful authentication, only
 the AUTHENTICATE, CAPABILITY, STARTTLS, LOGOUT, and NOOP (see Section
 2.13) commands are valid.  ManageSieve extensions MAY define other
 commands that are valid in non-authenticated state.  Servers MUST
 reject all other commands with a NO response.  Clients may pipeline
 commands (send more than one command at a time without waiting for
 completion of the first command).  However, a group of commands sent
 together MUST NOT have an AUTHENTICATE (*), a STARTTLS, or a
 HAVESPACE command anywhere but the last command in the list.
 (*) - The only exception to this rule is when the AUTHENTICATE
 command contains an initial response for a SASL mechanism that allows
 clients to send data first, the mechanism is known to complete in one
 round trip, and the mechanism doesn't negotiate a SASL security
 layer.  Two examples of such SASL mechanisms are PLAIN [PLAIN] and
 EXTERNAL [SASL].

Melnikov & Martin Standards Track [Page 10] RFC 5804 ManageSieve July 2010

2.1. AUTHENTICATE Command

 Arguments:  String - mechanism
             String - initial data (optional)
 The AUTHENTICATE command indicates a SASL [SASL] authentication
 mechanism to the server.  If the server supports the requested
 authentication mechanism, it performs an authentication protocol
 exchange to identify and authenticate the user.  Optionally, it also
 negotiates a security layer for subsequent protocol interactions.  If
 the requested authentication mechanism is not supported, the server
 rejects the AUTHENTICATE command by sending the NO response.
 The authentication protocol exchange consists of a series of server
 challenges and client responses that are specific to the selected
 authentication mechanism.  A server challenge consists of a string
 (quoted or literal) followed by a CRLF.  The contents of the string
 is a base-64 encoding [BASE64] of the SASL data.  A client response
 consists of a string (quoted or literal) with the base-64 encoding of
 the SASL data followed by a CRLF.  If the client wishes to cancel the
 authentication exchange, it issues a string containing a single "*".
 If the server receives such a response, it MUST reject the
 AUTHENTICATE command by sending a NO reply.
 Note that an empty challenge/response is sent as an empty string.  If
 the mechanism dictates that the final response is sent by the server,
 this data MAY be placed within the data portion of the SASL response
 code to save a round trip.
 The optional initial-response argument to the AUTHENTICATE command is
 used to save a round trip when using authentication mechanisms that
 are defined to send no data in the initial challenge.  When the
 initial-response argument is used with such a mechanism, the initial
 empty challenge is not sent to the client and the server uses the
 data in the initial-response argument as if it were sent in response
 to the empty challenge.  If the initial-response argument to the
 AUTHENTICATE command is used with a mechanism that sends data in the
 initial challenge, the server MUST reject the AUTHENTICATE command by
 sending the NO response.
 The service name specified by this protocol's profile of SASL is
 "sieve".
 Reauthentication is not supported by ManageSieve protocol's profile
 of SASL.  That is, after a successfully completed AUTHENTICATE
 command, no more AUTHENTICATE commands may be issued in the same
 session.  After a successful AUTHENTICATE command completes, a server
 MUST reject any further AUTHENTICATE commands with a NO reply.

Melnikov & Martin Standards Track [Page 11] RFC 5804 ManageSieve July 2010

 However, note that a server may implement the UNAUTHENTICATE
 extension described in Section 2.14.1.
 If a security layer is negotiated through the SASL authentication
 exchange, it takes effect immediately following the CRLF that
 concludes the successful authentication exchange for the client, and
 the CRLF of the OK response for the server.
 When a security layer takes effect, the ManageSieve protocol is reset
 to the initial state (the state in ManageSieve after a client has
 connected to the server).  The server MUST discard any knowledge
 obtained from the client that was not obtained from the SASL (or TLS)
 negotiation itself.  Likewise, the client MUST discard any knowledge
 obtained from the server, such as the list of ManageSieve extensions,
 that was not obtained from the SASL (and/or TLS) negotiation itself.
 (Note that a client MAY compare the advertised SASL mechanisms before
 and after authentication in order to detect an active down-
 negotiation attack.  See below.)
 Once a SASL security layer is established, the server MUST re-issue
 the capability results, followed by an OK response.  This is
 necessary to protect against man-in-the-middle attacks that alter the
 capabilities list prior to SASL negotiation.  The capability results
 MUST include all SASL mechanisms the server was capable of
 negotiating with that client.  This is done in order to allow the
 client to detect an active down-negotiation attack.  If a user-
 oriented client detects such a down-negotiation attack, it SHOULD
 either notify the user (it MAY give the user the opportunity to
 continue with the ManageSieve session in this case) or close the
 transport connection and indicate that a down-negotiation attack
 might be in progress.  If an automated client detects a down-
 negotiation attack, it SHOULD return or log an error indicating that
 a possible attack might be in progress and/or SHOULD close the
 transport connection.
 When both [TLS] and SASL security layers are in effect, the TLS
 encoding MUST be applied (when sending data) after the SASL encoding.
 Server implementations SHOULD support SASL proxy authentication so
 that an administrator can administer a user's scripts.  Proxy
 authentication is when a user authenticates as herself/himself but
 requests the server to act (authorize) as another user.
 The authorization identity generated by this [SASL] exchange is a
 "simple username" (in the sense defined in [SASLprep]), and both
 client and server MUST use the [SASLprep] profile of the [StringPrep]
 algorithm to prepare these names for transmission or comparison.  If
 preparation of the authorization identity fails or results in an

Melnikov & Martin Standards Track [Page 12] RFC 5804 ManageSieve July 2010

 empty string (unless it was transmitted as the empty string), the
 server MUST fail the authentication.
 If an AUTHENTICATE command fails with a NO response, the client MAY
 try another authentication mechanism by issuing another AUTHENTICATE
 command.  In other words, the client may request authentication types
 in decreasing order of preference.
 Note that a failed (NO) response to the AUTHENTICATE command may
 contain one of the following response codes: AUTH-TOO-WEAK, ENCRYPT-
 NEEDED, or TRANSITION-NEEDED.  See Section 1.3 for detailed
 description of the relevant conditions.
 To ensure interoperability, both client and server implementations of
 the ManageSieve protocol MUST implement the SCRAM-SHA-1 [SCRAM] SASL
 mechanism, as well as [PLAIN] over [TLS].
 Note: use of PLAIN over TLS reflects current use of PLAIN over TLS in
 other email-related protocols; however, a longer-term goal is to
 migrate email-related protocols from using PLAIN over TLS to SCRAM-
 SHA-1 mechanism.
 Examples (Note that long lines are folded for readability and are not
 part of protocol exchange):
     S: "IMPLEMENTATION" "Example1 ManageSieved v001"
     S: "SASL" "DIGEST-MD5 GSSAPI"
     S: "SIEVE" "fileinto vacation"
     S: "STARTTLS"
     S: "VERSION" "1.0"
     S: OK
     C: Authenticate "DIGEST-MD5"
     S: "cmVhbG09ImVsd29vZC5pbm5vc29mdC5leGFtcGxlLmNvbSIsbm9uY2U9Ik
        9BNk1HOXRFUUdtMmhoIixxb3A9ImF1dGgiLGFsZ29yaXRobT1tZDUtc2Vz
        cyxjaGFyc2V0PXV0Zi04"
     C: "Y2hhcnNldD11dGYtOCx1c2VybmFtZT0iY2hyaXMiLHJlYWxtPSJlbHdvb2
        QuaW5ub3NvZnQuZXhhbXBsZS5jb20iLG5vbmNlPSJPQTZNRzl0RVFHbTJo
        aCIsbmM9MDAwMDAwMDEsY25vbmNlPSJPQTZNSFhoNlZxVHJSayIsZGlnZX
        N0LXVyaT0ic2lldmUvZWx3b29kLmlubm9zb2Z0LmV4YW1wbGUuY29tIixy
        ZXNwb25zZT1kMzg4ZGFkOTBkNGJiZDc2MGExNTIzMjFmMjE0M2FmNyxxb3
        A9YXV0aA=="
     S: OK (SASL "cnNwYXV0aD1lYTQwZjYwMzM1YzQyN2I1NTI3Yjg0ZGJhYmNkZ
        mZmZA==")

Melnikov & Martin Standards Track [Page 13] RFC 5804 ManageSieve July 2010

 A slightly different variant of the same authentication exchange is:
     S: "IMPLEMENTATION" "Example1 ManageSieved v001"
     S: "SASL" "DIGEST-MD5 GSSAPI"
     S: "SIEVE" "fileinto vacation"
     S: "VERSION" "1.0"
     S: "STARTTLS"
     S: OK
     C: Authenticate "DIGEST-MD5"
     S: {136}
     S: cmVhbG09ImVsd29vZC5pbm5vc29mdC5leGFtcGxlLmNvbSIsbm9uY2U9Ik
        9BNk1HOXRFUUdtMmhoIixxb3A9ImF1dGgiLGFsZ29yaXRobT1tZDUtc2Vz
        cyxjaGFyc2V0PXV0Zi04
     C: {300+}
     C: Y2hhcnNldD11dGYtOCx1c2VybmFtZT0iY2hyaXMiLHJlYWxtPSJlbHdvb2
        QuaW5ub3NvZnQuZXhhbXBsZS5jb20iLG5vbmNlPSJPQTZNRzl0RVFHbTJo
        aCIsbmM9MDAwMDAwMDEsY25vbmNlPSJPQTZNSFhoNlZxVHJSayIsZGlnZX
        N0LXVyaT0ic2lldmUvZWx3b29kLmlubm9zb2Z0LmV4YW1wbGUuY29tIixy
        ZXNwb25zZT1kMzg4ZGFkOTBkNGJiZDc2MGExNTIzMjFmMjE0M2FmNyxxb3
        A9YXV0aA==
     S: {56}
     S: cnNwYXV0aD1lYTQwZjYwMzM1YzQyN2I1NTI3Yjg0ZGJhYmNkZmZmZA==
     C: ""
     S: OK

Melnikov & Martin Standards Track [Page 14] RFC 5804 ManageSieve July 2010

 Another example demonstrating use of SASL PLAIN mechanism under TLS
 follows.  This example also demonstrate use of SASL "initial
 response" (the second parameter to the Authenticate command):
     S: "IMPLEMENTATION" "Example1 ManageSieved v001"
     S: "VERSION" "1.0"
     S: "SASL" ""
     S: "SIEVE" "fileinto vacation"
     S: "STARTTLS"
     S: OK
     C: STARTTLS
     S: OK
     <TLS negotiation, further commands are under TLS layer>
     S: "IMPLEMENTATION" "Example1 ManageSieved v001"
     S: "VERSION" "1.0"
     S: "SASL" "PLAIN"
     S: "SIEVE" "fileinto vacation"
     S: OK
     C: Authenticate "PLAIN" "QJIrweAPyo6Q1T9xu"
     S: NO
     C: Authenticate "PLAIN" "QJIrweAPyo6Q1T9xz"
     S: NO
     C: Authenticate "PLAIN" "QJIrweAPyo6Q1T9xy"
     S: BYE "Too many failed authentication attempts"
     <Server closes connection>

Melnikov & Martin Standards Track [Page 15] RFC 5804 ManageSieve July 2010

 The following example demonstrates use of SASL "initial response".
 It also demonstrates that an empty response can be sent as a literal
 and that negotiating a SASL security layer results in the server
 re-issuing server capabilities:
     C: AUTHENTICATE "GSSAPI" {1488+}
     C: YIIE[...1480 octets here ...]dA==
     S: {208}
     S: YIGZBgkqhkiG9xIBAgICAG+BiTCBhqADAgEFoQMCAQ+iejB4oAMCARKic
        [...114 octets here ...]
        /yzpAy9p+Y0LanLskOTvMc0MnjgAa4YEr3eJ6
     C: {0+}
     C:
     S: {44}
     S: BQQF/wAMAAwAAAAAYRGFAo6W0vIHti8i1UXODgEAEAA=
     C: {44+}
     C: BQQE/wAMAAwAAAAAIsT1iv9UkZApw471iXt6cwEAAAE=
     S: OK
     <Further commands/responses are under SASL security layer>
     S: "IMPLEMENTATION" "Example1 ManageSieved v001"
     S: "VERSION" "1.0"
     S: "SASL" "PLAIN DIGEST-MD5 GSSAPI"
     S: "SIEVE" "fileinto vacation"
     S: "LANGUAGE" "ru"
     S: "MAXREDIRECTS" "3"
     S: ok

2.1.1. Use of SASL PLAIN Mechanism over TLS

 This section is normative for ManageSieve client implementations that
 support SASL [PLAIN] over [TLS].
 If a ManageSieve client is willing to use SASL PLAIN over TLS to
 authenticate to the ManageSieve server, the client MUST verify the
 server identity (see Section 2.2.1).  If the server identity can't be
 verified (e.g., the server has not provided any certificate, or if
 the certificate verification fails), the client MUST NOT attempt to
 authenticate using the SASL PLAIN mechanism.

2.2. STARTTLS Command

 Support for STARTTLS command in servers is optional.  Its
 availability is advertised with "STARTTLS" capability as described in
 Section 1.7.
 The STARTTLS command requests commencement of a TLS [TLS]
 negotiation.  The negotiation begins immediately after the CRLF in
 the OK response.  After a client issues a STARTTLS command, it MUST

Melnikov & Martin Standards Track [Page 16] RFC 5804 ManageSieve July 2010

 NOT issue further commands until a server response is seen and the
 TLS negotiation is complete.
 The STARTTLS command is only valid in non-authenticated state.  The
 server remains in non-authenticated state, even if client credentials
 are supplied during the TLS negotiation.  The SASL [SASL] EXTERNAL
 mechanism MAY be used to authenticate once TLS client credentials are
 successfully exchanged, but servers supporting the STARTTLS command
 are not required to support the EXTERNAL mechanism.
 After the TLS layer is established, the server MUST re-issue the
 capability results, followed by an OK response.  This is necessary to
 protect against man-in-the-middle attacks that alter the capabilities
 list prior to STARTTLS.  This capability result MUST NOT include the
 STARTTLS capability.
 The client MUST discard cached capability information and replace it
 with the new information.  The server MAY advertise different
 capabilities after STARTTLS.
     Example:
     C: StartTls
     S: oK
     <TLS negotiation, further commands are under TLS layer>
     S: "IMPLEMENTATION" "Example1 ManageSieved v001"
     S: "SASL" "PLAIN DIGEST-MD5 GSSAPI"
     S: "SIEVE" "fileinto vacation"
     S: "VERSION" "1.0"
     S: "LANGUAGE" "fr"
     S: ok

2.2.1. Server Identity Check

 During the TLS negotiation, the ManageSieve client MUST check its
 understanding of the server hostname/IP address against the server's
 identity as presented in the server Certificate message, in order to
 prevent man-in-the-middle attacks.  In this section, the client's
 understanding of the server's identity is called the "reference
 identity".
 Checking is performed according to the following rules:
 o  If the reference identity is a hostname:
    1.  If a subjectAltName extension of the SRVName [X509-SRV],
        dNSName [X509] (in that order of preference) type is present
        in the server's certificate, then it SHOULD be used as the

Melnikov & Martin Standards Track [Page 17] RFC 5804 ManageSieve July 2010

        source of the server's identity.  Matching is performed as
        described in Section 2.2.1.1, with the exception that no
        wildcard matching is allowed for SRVName type.  If the
        certificate contains multiple names (e.g., more than one
        dNSName field), then a match with any one of the fields is
        considered acceptable.
    2.  The client MAY use other types of subjectAltName for
        performing comparison.
    3.  The server's identity MAY also be verified by comparing the
        reference identity to the Common Name (CN) [RFC4519] value in
        the leaf Relative Distinguished Name (RDN) of the subjectName
        field of the server's certificate.  This comparison is
        performed using the rules for comparison of DNS names in
        Section 2.2.1.1, below.  Although the use of the Common Name
        value is existing practice, it is deprecated, and
        Certification Authorities are encouraged to provide
        subjectAltName values instead.  Note that the TLS
        implementation may represent DNs in certificates according to
        X.500 or other conventions.  For example, some X.500
        implementations order the RDNs in a DN using a left-to-right
        (most significant to least significant) convention instead of
        LDAP's right-to-left convention.
 o  When the reference identity is an IP address, the iPAddress
    subjectAltName SHOULD be used by the client for comparison.  The
    comparison is performed as described in Section 2.2.1.2.
 If the server identity check fails, user-oriented clients SHOULD
 either notify the user (clients MAY give the user the opportunity to
 continue with the ManageSieve session in this case) or close the
 transport connection and indicate that the server's identity is
 suspect.  Automated clients SHOULD return or log an error indicating
 that the server's identity is suspect and/or SHOULD close the
 transport connection.  Automated clients MAY provide a configuration
 setting that disables this check, but MUST provide a setting that
 enables it.
 Beyond the server identity check described in this section, clients
 should be prepared to do further checking to ensure that the server
 is authorized to provide the service it is requested to provide.  The
 client may need to make use of local policy information in making
 this determination.

Melnikov & Martin Standards Track [Page 18] RFC 5804 ManageSieve July 2010

2.2.1.1. Comparison of DNS Names

 If the reference identity is an internationalized domain name,
 conforming implementations MUST convert it to the ASCII Compatible
 Encoding (ACE) format as specified in Section 4 of RFC 3490 [RFC3490]
 before comparison with subjectAltName values of type dNSName.
 Specifically, conforming implementations MUST perform the conversion
 operation specified in Section 4 of [RFC3490] as follows:
 o  in step 1, the domain name SHALL be considered a "stored string";
 o  in step 3, set the flag called "UseSTD3ASCIIRules";
 o  in step 4, process each label with the "ToASCII" operation; and
 o  in step 5, change all label separators to U+002E (full stop).
 After performing the "to-ASCII" conversion, the DNS labels and names
 MUST be compared for equality according to the rules specified in
 Section 3 of [RFC3490]; i.e., once all label separators are replaced
 with U+002E (dot) they are compared in the case-insensitive manner.
 The '*' (ASCII 42) wildcard character is allowed in subjectAltName
 values of type dNSName, and then only as the left-most (least
 significant) DNS label in that value.  This wildcard matches any
 left-most DNS label in the server name.  That is, the subject
 *.example.com matches the server names a.example.com and
 b.example.com, but does not match example.com or a.b.example.com.

2.2.1.2. Comparison of IP Addresses

 When the reference identity is an IP address, the identity MUST be
 converted to the "network byte order" octet string representation
 [RFC791][RFC2460].  For IP Version 4, as specified in RFC 791, the
 octet string will contain exactly four octets.  For IP Version 6, as
 specified in RFC 2460, the octet string will contain exactly sixteen
 octets.  This octet string is then compared against subjectAltName
 values of type iPAddress.  A match occurs if the reference identity
 octet string and value octet strings are identical.

2.2.1.3. Comparison of Other subjectName Types

 Client implementations MAY support matching against subjectAltName
 values of other types as described in other documents.

Melnikov & Martin Standards Track [Page 19] RFC 5804 ManageSieve July 2010

2.3. LOGOUT Command

 The client sends the LOGOUT command when it is finished with a
 connection and wishes to terminate it.  The server MUST reply with an
 OK response.  The server MUST ignore commands issued by the client
 after the LOGOUT command.
 The client SHOULD wait for the OK response before closing the
 connection.  This avoids the TCP connection going into the TIME_WAIT
 state on the server.  In order to avoid going into the TIME_WAIT TCP
 state, the server MAY wait for a short while for the client to close
 the TCP connection first.  Whether or not the server waits for the
 client to close the connection, it MUST then close the connection
 itself.
     Example:
     C: Logout
     S: Ok
     <connection is terminated>

2.4. CAPABILITY Command

 The CAPABILITY command requests the server capabilities as described
 earlier in this document.  It has no parameters.
     Example:
     C: CAPABILITY
     S: "IMPLEMENTATION" "Example1 ManageSieved v001"
     S: "VERSION" "1.0"
     S: "SASL" "PLAIN SCRAM-SHA-1 GSSAPI"
     S: "SIEVE" "fileinto vacation"
     S: "STARTTLS"
     S: OK

2.5. HAVESPACE Command

 Arguments:  String - name
             Number - script size
 The HAVESPACE command is used to query the server for available
 space.  Clients specify the name they wish to save the script as and
 its size in octets.  Both parameters can be used by the server to see
 if the script with the specified name and size is within a user's
 quota(s).  For example, the server MAY use the script name to check
 if a script would be replaced or a new one would be created.  Servers
 respond with a NO if storing a script with that name and size would

Melnikov & Martin Standards Track [Page 20] RFC 5804 ManageSieve July 2010

 fail or OK otherwise.  Clients SHOULD issue this command before
 attempting to place a script on the server.
 Note that the OK response from the HAVESPACE command does not
 constitute a guarantee of success as server disk space conditions
 could change between the client issuing the HAVESPACE and the client
 issuing the PUTSCRIPT commands.  A QUOTA response code (see
 Section 1.3) remains a possible (albeit unlikely) response to a
 subsequent PUTSCRIPT with the same name and size.
     Example:
     C: HAVESPACE "myscript" 999999
     S: NO (QUOTA/MAXSIZE) "Quota exceeded"
     C: HAVESPACE "foobar" 435
     S: OK

2.6. PUTSCRIPT Command

 Arguments:  String - Script name
             String - Script content
 The PUTSCRIPT command is used by the client to submit a Sieve script
 to the server.
 If the script already exists, upon success the old script will be
 overwritten.  The old script MUST NOT be overwritten if PUTSCRIPT
 fails in any way.  A script of zero length SHOULD be disallowed.
 This command places the script on the server.  It does not affect
 whether the script is processed on incoming mail, unless it replaces
 the script that is already active.  The SETACTIVE command is used to
 mark a script as active.
 When submitting large scripts, clients SHOULD use the HAVESPACE
 command beforehand to query if the server is willing to accept a
 script of that size.
 The server MUST check the submitted script for validity, which
 includes checking that the script complies with the Sieve grammar
 [SIEVE] and that all Sieve extensions mentioned in the script's
 "require" statement(s) are supported by the Sieve interpreter.  (Note
 that if the Sieve interpreter supports the Sieve "ihave" extension
 [I-HAVE], any unrecognized/unsupported extension mentioned in the
 "ihave" test MUST NOT cause the validation failure.)  Other checks
 such as validating the supplied command arguments for each command
 MAY be performed.  Essentially, the performed validation SHOULD be

Melnikov & Martin Standards Track [Page 21] RFC 5804 ManageSieve July 2010

 the same as performed when compiling the script for execution.
 Implementations that use a binary representation to store compiled
 scripts can extend the validation to a full compilation, in order to
 avoid validating uploaded scripts multiple times.
 If the script fails the validation, the server MUST reply with a NO
 response.  Any script that fails the validity test MUST NOT be stored
 on the server.  The message given with a NO response MUST be human
 readable and SHOULD contain a specific error message giving the line
 number of the first error.  Implementors should strive to produce
 helpful error messages similar to those given by programming language
 compilers.  Client implementations should note that this may be a
 multiline literal string with more than one error message separated
 by CRLFs.  The human-readable message is in the language returned in
 the latest LANGUAGE capability (or in "i-default"; see Section 1.7),
 encoded in UTF-8 [UTF-8].
 An OK response MAY contain the WARNINGS response code.  In such a
 case the human-readable message that follows the OK response SHOULD
 contain a specific warning message (or messages) giving the line
 number(s) in the script that might contain errors not intended by the
 script writer.  The human-readable message is in the language
 returned in the latest LANGUAGE capability (or in "i-default"; see
 Section 1.7), encoded in UTF-8 [UTF-8].  A client seeing such a
 response code SHOULD present the message to the user.

Melnikov & Martin Standards Track [Page 22] RFC 5804 ManageSieve July 2010

     Examples:
     C: Putscript "foo" {31+}
     C: #comment
     C: InvalidSieveCommand
     C:
     S: NO "line 2: Syntax error"
     C: Putscript "mysievescript" {110+}
     C: require ["fileinto"];
     C:
     C: if envelope :contains "to" "tmartin+sent" {
     C:   fileinto "INBOX.sent";
     C: }
     S: OK
     C: Putscript "myforwards" {190+}
     C: redirect "111@example.net";
     C:
     C: if size :under 10k {
     C:     redirect "mobile@cell.example.com";
     C: }
     C:
     C: if envelope :contains "to" "tmartin+lists" {
     C:     redirect "lists@groups.example.com";
     C: }
     S: OK (WARNINGS) "line 8: server redirect action
             limit is 2, this redirect might be ignored"

2.7. LISTSCRIPTS Command

 This command lists the scripts the user has on the server.  Upon
 success, a list of CRLF-separated script names (each represented as a
 quoted or literal string) is returned followed by an OK response.  If
 there exists an active script, the atom ACTIVE is appended to the
 corresponding script name.  The atom ACTIVE MUST NOT appear on more
 than one response line.

Melnikov & Martin Standards Track [Page 23] RFC 5804 ManageSieve July 2010

     Example:
     C: Listscripts
     S: "summer_script"
     S: "vacation_script"
     S: {13}
     S: clever"script
     S: "main_script" ACTIVE
     S: OK
     C: listscripts
     S: "summer_script"
     S: "main_script" active
     S: OK

2.8. SETACTIVE Command

 Arguments:  String - script name
 This command sets a script active.  If the script name is the empty
 string (i.e., ""), then any active script is disabled.  Disabling an
 active script when there is no script active is not an error and MUST
 result in an OK reply.
 If the script does not exist on the server, then the server MUST
 reply with a NO response.  Such a reply SHOULD contain the
 NONEXISTENT response code.
     Examples:
     C: Setactive "vacationscript"
     S: Ok
     C: Setactive ""
     S: Ok
     C: Setactive "baz"
     S: No (NONEXISTENT) "There is no script by that name"
     C: Setactive "baz"
     S: No (NONEXISTENT) {31}
     S: There is no script by that name

Melnikov & Martin Standards Track [Page 24] RFC 5804 ManageSieve July 2010

2.9. GETSCRIPT Command

 Arguments:  String - script name
 This command gets the contents of the specified script.  If the
 script does not exist, the server MUST reply with a NO response.
 Such a reply SHOULD contain the NONEXISTENT response code.
 Upon success, a string with the contents of the script is returned
 followed by an OK response.
     Example:
     C: Getscript "myscript"
     S: {54}
     S: #this is my wonderful script
     S: reject "I reject all";
     S:
     S: OK

2.10. DELETESCRIPT Command

 Arguments:  String - script name
 This command is used to delete a user's Sieve script.  Servers MUST
 reply with a NO response if the script does not exist.  Such
 responses SHOULD include the NONEXISTENT response code.
 The server MUST NOT allow the client to delete an active script, so
 the server MUST reply with a NO response if attempted.  Such a
 response SHOULD contain the ACTIVE response code.  If a client wishes
 to delete an active script, it should use the SETACTIVE command to
 disable the script first.
     Example:
     C: Deletescript "foo"
     S: Ok
     C: Deletescript "baz"
     S: No (ACTIVE) "You may not delete an active script"

Melnikov & Martin Standards Track [Page 25] RFC 5804 ManageSieve July 2010

2.11. RENAMESCRIPT Command

 Arguments:  String - Old Script name
             String - New Script name
 This command is used to rename a user's Sieve script.  Servers MUST
 reply with a NO response if the old script does not exist (in which
 case the NONEXISTENT response code SHOULD be included), or a script
 with the new name already exists (in which case the ALREADYEXISTS
 response code SHOULD be included).  Renaming the active script is
 allowed; the renamed script remains active.
     Example:
     C: Renamescript "foo" "bar"
     S: Ok
     C: Renamescript "baz" "bar"
     S: No "bar already exists"
 If the server doesn't support the RENAMESCRIPT command, the client
 can emulate it by performing the following steps:
 1.  List available scripts with LISTSCRIPTS.  If the script with the
     new script name exists, then the client should ask the user
     whether to abort the operation, to replace the script (by issuing
     the DELETESCRIPT <newname> after that), or to choose a different
     name.
 2.  Download the old script with GETSCRIPT <oldname>.
 3.  Upload the old script with the new name: PUTSCRIPT <newname>.
 4.  If the old script was active (as reported by LISTSCRIPTS in step
     1), then make the new script active: SETACTIVE <newname>.
 5.  Delete the old script: DELETESCRIPT <oldname>.
 Note that these steps don't describe how to handle various other
 error conditions (for example, NO response containing QUOTA response
 code in step 3).  Error handling is left as an exercise for the
 reader.

Melnikov & Martin Standards Track [Page 26] RFC 5804 ManageSieve July 2010

2.12. CHECKSCRIPT Command

 Arguments:  String - Script content
 The CHECKSCRIPT command is used by the client to verify Sieve script
 validity without storing the script on the server.
 The server MUST check the submitted script for syntactic validity,
 which includes checking that all Sieve extensions mentioned in Sieve
 script "require" statement(s) are supported by the Sieve interpreter.
 (Note that if the Sieve interpreter supports the Sieve "ihave"
 extension [I-HAVE], any unrecognized/unsupported extension mentioned
 in the "ihave" test MUST NOT cause the syntactic validation failure.)
 If the script fails this test, the server MUST reply with a NO
 response.  The message given with a NO response MUST be human
 readable and SHOULD contain a specific error message giving the line
 number of the first error.  Implementors should strive to produce
 helpful error messages similar to those given by programming language
 compilers.  Client implementations should note that this may be a
 multiline literal string with more than one error message separated
 by CRLFs.  The human-readable message is in the language returned in
 the latest LANGUAGE capability (or in "i-default"; see Section 1.7),
 encoded in UTF-8 [UTF-8].
     Examples:
     C: CheckScript {31+}
     C: #comment
     C: InvalidSieveCommand
     C:
     S: NO "line 2: Syntax error"
 A ManageSieve server supporting this command MUST NOT check if the
 script will put the current user over its quota limit.
 An OK response MAY contain the WARNINGS response code.  In such a
 case, the human-readable message that follows the OK response SHOULD
 contain a specific warning message (or messages) giving the line
 number(s) in the script that might contain errors not intended by the
 script writer.  The human-readable message is in the language
 returned in the latest LANGUAGE capability (or in "i-default"; see
 Section 1.7), encoded in UTF-8 [UTF-8].  A client seeing such a
 response code SHOULD present the message to the user.

Melnikov & Martin Standards Track [Page 27] RFC 5804 ManageSieve July 2010

2.13. NOOP Command

 Arguments:  String - tag to echo back (optional)
 The NOOP command does nothing, beyond returning a response to the
 client.  It may be used by clients for protocol re-synchronization or
 to reset any inactivity auto-logout timer on the server.
 The response to the NOOP command is always OK, followed by the TAG
 response code together with the supplied string.  If no string was
 supplied in the NOOP command, the TAG response code MUST NOT be
 included.
     Examples:
     C: NOOP
     S: OK "NOOP completed"
     C: NOOP "STARTTLS-SYNC-42"
     S: OK (TAG {16}
     S: STARTTLS-SYNC-42) "Done"

2.14. Recommended Extensions

 The UNAUTHENTICATE extension (advertised as the "UNAUTHENTICATE"
 capability with no parameters) defines a new UNAUTHENTICATE command,
 which allows a client to return the server to non-authenticated
 state.  Support for this extension is RECOMMENDED.

2.14.1. UNAUTHENTICATE Command

 The UNAUTHENTICATE command returns the server to the
 non-authenticated state.  It doesn't affect any previously
 established TLS [TLS] or SASL (Section 2.1) security layer.
 The UNAUTHENTICATE command is only valid in authenticated state.  If
 issued in a wrong state, the server MUST reject it with a NO
 response.
 The UNAUTHENTICATE command has no parameters.
 When issued in the authenticated state, the UNAUTHENTICATE command
 MUST NOT fail (i.e., it must never return anything other than OK or
 BYE).

Melnikov & Martin Standards Track [Page 28] RFC 5804 ManageSieve July 2010

3. Sieve URL Scheme

 URI scheme name: sieve
 Status: permanent
 URI scheme syntax: Described using ABNF [ABNF].  Some ABNF
 productions not defined below are from [URI-GEN].
       sieveurl = sieveurl-server / sieveurl-list-scripts /
                  sieveurl-script
       sieveurl-server = "sieve://" authority
       sieveurl-list-scripts = "sieve://" authority ["/"]
       sieveurl-script = "sieve://" authority "/"
                         [owner "/"] scriptname
       authority = <defined in [URI-GEN]>
       owner         = *ochar
                       ;; %-encoded version of [SASL] authorization
                       ;; identity (script owner) or "userid".
                       ;;
                       ;; Empty owner is used to reference
                       ;; global scripts.
                       ;;
                       ;; Note that ASCII characters such as " ", ";",
                       ;; "&", "=", "/" and "?" must be %-encoded
                       ;; as per rule specified in [URI-GEN].
       scriptname    = 1*ochar
                       ;; %-encoded version of UTF-8 representation
                       ;; of the script name.
                       ;; Note that ASCII characters such as " ", ";",
                       ;; "&", "=", "/" and "?" must be %-encoded
                       ;; as per rule specified in [URI-GEN].
       ochar         = unreserved / pct-encoded / sub-delims-sh /
                       ":" / "@"
                       ;; Same as [URI-GEN] 'pchar',
                       ;; but without ";", "&" and "=".
       unreserved = <defined in [URI-GEN]>
       pct-encoded = <defined in [URI-GEN]>

Melnikov & Martin Standards Track [Page 29] RFC 5804 ManageSieve July 2010

       sub-delims-sh = "!" / "$" / "'" / "(" / ")" /
                       "*" / "+" / ","
                       ;; Same as [URI-GEN] sub-delims,
                       ;; but without ";", "&" and "=".
 URI scheme semantics:
    A Sieve URL identifies a Sieve server or a Sieve script on a Sieve
    server.  The latter form is associated with the application/sieve
    MIME type defined in [SIEVE].  There is no MIME type associated
    with the former form of Sieve URI.
    The server form is used in the REFERRAL response code (see Section
    1.3) in order to designate another server where the client should
    perform its operations.
    The script form allows to retrieve (GETSCRIPT), update
    (PUTSCRIPT), delete (DELETESCRIPT), or activate (SETACTIVE) the
    named script; however, the most typical action would be to
    retrieve the script.  If the script name is empty (omitted), the
    URI requests that the client lists available scripts using the
    LISTSCRIPTS command.
 Encoding considerations:
    The script name and/or the owner, if present, is in UTF-8.  Non--
    US-ASCII UTF-8 octets MUST be percent-encoded as described in
    [URI-GEN].  US-ASCII characters such as " " (space), ";", "&",
    "=", "/" and "?"  MUST be %-encoded as described in [URI-GEN].
    Note that "&" and "?" are in this list in order to allow for
    future extensions.
    Note that the empty owner (e.g., sieve://example.com//script) is
    different from the missing owner (e.g.,
    sieve://example.com/script) and is reserved for referencing global
    scripts.
    The user name (in the "authority" part), if present, is in UTF-8.
    Non-US-ASCII UTF-8 octets MUST be percent-encoded as described in
    [URI-GEN].
 Applications/protocols that use this URI scheme name:
 ManageSieve [RFC5804] clients and servers.  Clients that can store
 user preferences in protocols such as [LDAP] or [ACAP].
 Interoperability considerations: None.

Melnikov & Martin Standards Track [Page 30] RFC 5804 ManageSieve July 2010

 Security considerations:
 The <scriptname> part of a ManageSieve URL might potentially disclose
 some confidential information about the author of the script or,
 depending on a ManageSieve implementation, about configuration of the
 mail system.  The latter might be used to prepare for a more complex
 attack on the mail system.
 Clients resolving ManageSieve URLs that wish to achieve data
 confidentiality and/or integrity SHOULD use the STARTTLS command (if
 supported by the server) before starting authentication, or use a
 SASL mechanism, such as GSSAPI, that provides a confidentiality
 security layer.
 Contact: Alexey Melnikov <alexey.melnikov@isode.com>
 Author/Change controller: IESG.
 References: This document and RFC 5228 [SIEVE].

4. Formal Syntax

 The following syntax specification uses the Augmented Backus-Naur
 Form (BNF) notation as specified in [ABNF].  This uses the ABNF core
 rules as specified in Appendix A of the ABNF specification [ABNF].
 "UTF8-2", "UTF8-3", and "UTF8-4" non-terminal are defined in [UTF-8].
 Except as noted otherwise, all alphabetic characters are case-
 insensitive.  The use of upper- or lowercase characters to define
 token strings is for editorial clarity only.  Implementations MUST
 accept these strings in a case-insensitive fashion.
  SAFE-CHAR             = %x01-09 / %x0B-0C / %x0E-21 / %x23-5B /
                          %x5D-7F
                          ;; any TEXT-CHAR except QUOTED-SPECIALS
  QUOTED-CHAR           = SAFE-UTF8-CHAR / "\" QUOTED-SPECIALS
  QUOTED-SPECIALS       = DQUOTE / "\"
  SAFE-UTF8-CHAR        = SAFE-CHAR / UTF8-2 / UTF8-3 / UTF8-4
                          ;; <UTF8-2>, <UTF8-3>, and <UTF8-4>
                          ;; are defined in [UTF-8].
  ATOM-CHAR             = "!" / %x23-27 / %x2A-5B / %x5D-7A / %x7C-7E
                          ;; Any CHAR except ATOM-SPECIALS
  ATOM-SPECIALS         = "(" / ")" / "{" / SP / CTL / QUOTED-SPECIALS

Melnikov & Martin Standards Track [Page 31] RFC 5804 ManageSieve July 2010

  NZDIGIT               = %x31-39
                          ;; 1-9
  atom                  = 1*1024ATOM-CHAR
  iana-token            = atom
                          ;; MUST be registered with IANA
  auth-type             = DQUOTE auth-type-name DQUOTE
  auth-type-name        = iana-token
                          ;; as defined in SASL [SASL]
  command               = (command-any / command-auth /
                           command-nonauth) CRLF
                          ;; Modal based on state
  command-any           = command-capability / command-logout /
                          command-noop
                          ;; Valid in all states
  command-auth          = command-getscript / command-setactive /
                          command-listscripts / command-deletescript /
                          command-putscript / command-checkscript /
                          command-havespace /
                          command-renamescript /
                          command-unauthenticate
                          ;; Valid only in Authenticated state
  command-nonauth       = command-authenticate / command-starttls
                          ;; Valid only when in Non-Authenticated
                          ;; state
  command-authenticate  = "AUTHENTICATE" SP auth-type [SP string]
                          *(CRLF string)
  command-capability    = "CAPABILITY"
  command-deletescript  = "DELETESCRIPT" SP sieve-name
  command-getscript     = "GETSCRIPT" SP sieve-name
  command-havespace     = "HAVESPACE" SP sieve-name SP number
  command-listscripts   = "LISTSCRIPTS"
  command-noop          = "NOOP" [SP string]

Melnikov & Martin Standards Track [Page 32] RFC 5804 ManageSieve July 2010

  command-logout        = "LOGOUT"
  command-putscript     = "PUTSCRIPT" SP sieve-name SP sieve-script
  command-checkscript   = "CHECKSCRIPT" SP sieve-script
  sieve-script          = string
  command-renamescript  = "RENAMESCRIPT" SP old-sieve-name SP
                          new-sieve-name
  old-sieve-name        = sieve-name
  new-sieve-name        = sieve-name
  command-setactive     = "SETACTIVE" SP active-sieve-name
  command-starttls      = "STARTTLS"
  command-unauthenticate= "UNAUTHENTICATE"
  extend-token          = atom
                          ;; MUST be defined by a Standards Track or
                          ;; IESG-approved experimental protocol
                          ;; extension
  extension-data        = extension-item *(SP extension-item)
  extension-item        = extend-token / string / number /
                          "(" [extension-data] ")"
  literal-c2s           = "{" number "+}" CRLF *OCTET
                          ;; The number represents the number of
                          ;; octets.
                          ;; This type of literal can only be sent
                          ;; from the client to the server.
  literal-s2c           = "{" number "}" CRLF *OCTET
                          ;; Almost identical to literal-c2s,
                          ;; but with no '+' character.
                          ;; The number represents the number of
                          ;; octets.
                          ;; This type of literal can only be sent
                          ;; from the server to the client.

Melnikov & Martin Standards Track [Page 33] RFC 5804 ManageSieve July 2010

  number                = (NZDIGIT *DIGIT) / "0"
                          ;; A 32-bit unsigned number
                          ;; with no extra leading zeros.
                          ;; (0 <= n < 4,294,967,296)
  number-str            = string
                          ;; <number> encoded as a <string>.
  quoted                = DQUOTE *1024QUOTED-CHAR DQUOTE
                          ;; limited to 1024 octets between the <">s
  resp-code             = "AUTH-TOO-WEAK" / "ENCRYPT-NEEDED" / "QUOTA"
                          ["/" ("MAXSCRIPTS" / "MAXSIZE")] /
                          resp-code-sasl /
                          resp-code-referral /
                          "TRANSITION-NEEDED" / "TRYLATER" /
                          "ACTIVE" / "NONEXISTENT" /
                          "ALREADYEXISTS" / "WARNINGS" /
                          "TAG" SP string /
                          resp-code-ext
  resp-code-referral    = "REFERRAL" SP sieveurl
  resp-code-sasl        = "SASL" SP string
  resp-code-name        = iana-token
                          ;; The response code name is hierarchical,
                          ;; separated by '/'.
                          ;; The response code name MUST NOT start
                          ;; with '/'.
  resp-code-ext         = resp-code-name [SP extension-data]
                          ;; unknown response codes MUST be tolerated
                          ;; by the client.
  response              = response-authenticate /
                          response-logout /
                          response-getscript /
                          response-setactive /
                          response-listscripts /
                          response-deletescript /
                          response-putscript /
                          response-checkscript /
                          response-capability /
                          response-havespace /
                          response-starttls /
                          response-renamescript /
                          response-noop /

Melnikov & Martin Standards Track [Page 34] RFC 5804 ManageSieve July 2010

                          response-unauthenticate
  response-authenticate = *(string CRLF)
                          ((response-ok [response-capability]) /
                           response-nobye)
                          ;; <response-capability> is REQUIRED if a
                          ;; SASL security layer was negotiated and
                          ;; MUST be omitted otherwise.
  response-capability   = *(single-capability) response-oknobye
  single-capability     = capability-name [SP string] CRLF
  capability-name       = string
                          ;; Note that literal-s2c is allowed.
  initial-capabilities  = DQUOTE "IMPLEMENTATION" DQUOTE SP string /
                          DQUOTE "SASL" DQUOTE SP sasl-mechs /
                          DQUOTE "SIEVE" DQUOTE SP sieve-extensions /
                          DQUOTE "MAXREDIRECTS" DQUOTE SP number-str /
                          DQUOTE "NOTIFY" DQUOTE SP notify-mechs /
                          DQUOTE "STARTTLS" DQUOTE /
                          DQUOTE "LANGUAGE" DQUOTE SP language /
                          DQUOTE "VERSION" DQUOTE SP version /
                          DQUOTE "OWNER" DQUOTE SP string
                          ;; Each capability conforms to
                          ;; the syntax for single-capability.
                          ;; Also, note that the capability name
                          ;; can be returned as either literal-s2c
                          ;; or quoted, even though only "quoted"
                          ;; string is shown above.
  version = ( DQUOTE "1.0" DQUOTE ) / version-ext
  version-ext = DQUOTE ver-major "." ver-minor DQUOTE
               ; Future versions specified in updates
               ; to this document.  An increment to
               ; the ver-major means a backward-incompatible
               ; change to the protocol, e.g., "3.5" (ver-major "3")
               ; is not backward-compatible with any "2.X" version.
               ; Any version "Z.W" MUST be backward compatible
               ; with any version "Z.Q", where Q < W.
               ; For example, version "2.4" is backward compatible
               ; with version "2.0", "2.1", "2.2", and "2.3".
  ver-major = number

Melnikov & Martin Standards Track [Page 35] RFC 5804 ManageSieve July 2010

  ver-minor = number
  sasl-mechs = string
               ; Space-separated list of SASL mechanisms,
               ; each SASL mechanism name complies with rules
               ; specified in [SASL].
               ; Can be empty.
  sieve-extensions = string
               ; Space-separated list of supported SIEVE extensions.
               ; Can be empty.
  language     = string
               ; Contains <Language-Tag> from [RFC5646].
  notify-mechs = string
               ; Space-separated list of URI schema parts
               ; for supported notification [NOTIFY] methods.
               ; MUST NOT be empty.
  response-deletescript = response-oknobye
  response-getscript    = (sieve-script CRLF response-ok) /
                          response-nobye
  response-havespace    = response-oknobye
  response-listscripts  = *(sieve-name [SP "ACTIVE"] CRLF)
                          response-oknobye
                          ;; ACTIVE may only occur with one sieve-name
  response-logout       = response-oknobye
  response-unauthenticate= response-oknobye
                           ;; "NO" response can only be returned when
                           ;; the command is issued in a wrong state
                           ;; or has a wrong number of parameters
  response-ok           = "OK" [SP "(" resp-code ")"]
                          [SP string] CRLF
                          ;; The string contains human-readable text
                          ;; encoded as UTF-8.
  response-nobye        = ("NO" / "BYE") [SP "(" resp-code ")"]
                          [SP string] CRLF
                          ;; The string contains human-readable text
                          ;; encoded as UTF-8.

Melnikov & Martin Standards Track [Page 36] RFC 5804 ManageSieve July 2010

  response-oknobye      = response-ok / response-nobye
  response-noop         = response-ok
  response-putscript    = response-oknobye
  response-checkscript  = response-oknobye
  response-renamescript = response-oknobye
  response-setactive    = response-oknobye
  response-starttls     = (response-ok response-capability) /
                          response-nobye
  sieve-name            = string
                          ;; See Section 1.6 for the full list of
                          ;; prohibited characters.
                          ;; Empty string is not allowed.
  active-sieve-name     = string
                          ;; See Section 1.6 for the full list of
                          ;; prohibited characters.
                          ;; This is similar to <sieve-name>, but
                          ;; empty string is allowed and has a special
                          ;; meaning.
  string                = quoted / literal-c2s / literal-s2c
                          ;; literal-c2s is only allowed when sent
                          ;; from the client to the server.
                          ;; literal-s2c is only allowed when sent
                          ;; from the server to the client.
                          ;; quoted is allowed in either direction.

5. Security Considerations

 The AUTHENTICATE command uses SASL [SASL] to provide authentication
 and authorization services.  Integrity and privacy services can be
 provided by [SASL] and/or [TLS].  When a SASL mechanism is used, the
 security considerations for that mechanism apply.
 This protocol's transactions are susceptible to passive observers or
 man-in-the-middle attacks that alter the data, unless the optional
 encryption and integrity services of the SASL (via the AUTHENTICATE
 command) and/or [TLS] (via the STARTTLS command) are enabled, or an
 external security mechanism is used for protection.  It may be useful
 to allow configuration of both clients and servers to refuse to
 transfer sensitive information in the absence of strong encryption.

Melnikov & Martin Standards Track [Page 37] RFC 5804 ManageSieve July 2010

 If an implementation supports SASL mechanisms that are vulnerable to
 passive eavesdropping attacks (such as [PLAIN]), then the
 implementation MUST support at least one configuration where these
 SASL mechanisms are not advertised or used without the presence of an
 external security layer such as [TLS].
 Some response codes returned on failed AUTHENTICATE command may
 disclose whether or not the username is valid (e.g., TRANSITION-
 NEEDED), so server implementations SHOULD provide the ability to
 disable these features (or make them not conditional on a per-user
 basis) for sites concerned about such disclosure.  In the case of
 ENCRYPT-NEEDED, if it is applied to all identities then no extra
 information is disclosed, but if it is applied on a per-user basis it
 can disclose information.
 A compromised or malicious server can use the TRANSITION-NEEDED
 response code to force the client that is configured to use a
 mechanism that does not disclose the user's password to the server
 (e.g., Kerberos), to send the bare password to the server.  Clients
 SHOULD have the ability to disable the password transition feature,
 or disclose that risk to the user and offer the user an option of how
 to proceed.

6. IANA Considerations

 IANA has reserved TCP port number 4190 for use with the ManageSieve
 protocol described in this document.
 IANA has registered the "sieve" URI scheme defined in Section 3 of
 this document.
 IANA has registered "sieve" in the "GSSAPI/Kerberos/SASL Service
 Names" registry.
 IANA has created a new registry for ManageSieve capabilities.  The
 registration template for ManageSieve capabilities is specified in
 Section 6.1.  ManageSieve protocol capabilities MUST be specified in
 a Standards-Track or IESG-approved Experimental RFC.
 IANA has created a new registry for ManageSieve response codes.  The
 registration template for ManageSieve response codes is specified in
 Section 6.3.  ManageSieve protocol response codes MUST be specified
 in a Standards-Track or IESG-approved Experimental RFC.

Melnikov & Martin Standards Track [Page 38] RFC 5804 ManageSieve July 2010

6.1. ManageSieve Capability Registration Template

 To: iana@iana.org
 Subject: ManageSieve Capability Registration
 Please register the following ManageSieve capability:
 Capability name:
 Description:
 Relevant publications:
 Person & email address to contact for further information:
 Author/Change controller:

6.2. Registration of Initial ManageSieve Capabilities

 To: iana@iana.org
 Subject: ManageSieve Capability Registration
 Please register the following ManageSieve capabilities:
 Capability name:  IMPLEMENTATION
 Description:   Its value contains the name of the server
                implementation and its version.
 Relevant publications:  this RFC, Section 1.7.
 Person & email address to contact for further information:
                Alexey Melnikov <alexey.melnikov@isode.com>
 Author/Change controller:  IESG.
 Capability name:  SASL
 Description:   Its value contains a space-separated list of SASL
                mechanisms supported by the server.
 Relevant publications:  this RFC, Sections 1.7 and 2.1.
 Person & email address to contact for further information:
                Alexey Melnikov <alexey.melnikov@isode.com>
 Author/Change controller:  IESG.
 Capability name:  SIEVE
 Description:   Its value contains a space-separated list of supported
                SIEVE extensions.
 Relevant publications:  this RFC, Section 1.7.  Also [SIEVE].
 Person & email address to contact for further information:
                Alexey Melnikov <alexey.melnikov@isode.com>
 Author/Change controller:  IESG.

Melnikov & Martin Standards Track [Page 39] RFC 5804 ManageSieve July 2010

 Capability name:  STARTTLS
 Description:   This capability is returned if the server supports TLS
                (STARTTLS command).
 Relevant publications:  this RFC, Sections 1.7 and 2.2.
 Person & email address to contact for further information:
                Alexey Melnikov <alexey.melnikov@isode.com>
 Author/Change controller:  IESG.
 Capability name:  NOTIFY
 Description:   This capability is returned if the server supports the
                'enotify' [NOTIFY] Sieve extension.
 Relevant publications:  this RFC, Section 1.7.
 Person & email address to contact for further information:
                Alexey Melnikov <alexey.melnikov@isode.com>
 Author/Change controller:  IESG.
 Capability name:  MAXREDIRECTS
 Description:   This capability returns the limit on the number of
                Sieve "redirect" actions a script can perform during a
                single evaluation.  The value is a non-negative number
                represented as a ManageSieve string.
 Relevant publications:  this RFC, Section 1.7.
 Person & email address to contact for further information:
                Alexey Melnikov <alexey.melnikov@isode.com>
 Author/Change controller:  IESG.
 Capability name:  LANGUAGE
 Description:   The language (<Language-Tag> from [RFC5646]) currently
                used for human-readable error messages.
 Relevant publications:  this RFC, Section 1.7.
 Person & email address to contact for further information:
                Alexey Melnikov <alexey.melnikov@isode.com>
 Author/Change controller:  IESG.
 Capability name:  OWNER
 Description:   Its value contains the UTF-8-encoded name of the
                currently logged-in user ("authorization identity"
                according to RFC 4422).
 Relevant publications:  this RFC, Section 1.7.
 Person & email address to contact for further information:
                Alexey Melnikov <alexey.melnikov@isode.com>
 Author/Change controller:  IESG.

Melnikov & Martin Standards Track [Page 40] RFC 5804 ManageSieve July 2010

 Capability name:  VERSION
 Description:   This capability is returned if the server is compliant
                with RFC 5804; i.e., that it supports RENAMESCRIPT,
                CHECKSCRIPT, and NOOP commands.
 Relevant publications:  this RFC, Sections 2.11, 2.12, and 2.13.
 Person & email address to contact for further information:
                Alexey Melnikov <alexey.melnikov@isode.com>
 Author/Change controller:  IESG.

6.3. ManageSieve Response Code Registration Template

 To: iana@iana.org
 Subject: ManageSieve Response Code Registration
 Please register the following ManageSieve response code:
    Response Code:
    Arguments (use ABNF to specify syntax, or the word NONE if none
    can be specified):
    Purpose:
    Published Specification(s):
    Person & email address to contact for further information:
    Author/Change controller:

6.4. Registration of Initial ManageSieve Response Codes

 To: iana@iana.org
 Subject: ManageSieve Response Code Registration
 Please register the following ManageSieve response codes:
 Response Code: AUTH-TOO-WEAK
 Arguments (use ABNF to specify syntax, or the word NONE if none can
 be specified):  NONE
 Purpose:       This response code is returned in the NO response from
                an AUTHENTICATE command.  It indicates that site
                security policy forbids the use of the requested
                mechanism for the specified authentication identity.
 Published Specification(s):  [RFC5804]
 Person & email address to contact for further information:
                Alexey Melnikov <alexey.melnikov@isode.com>
 Author/Change controller:  IESG.

Melnikov & Martin Standards Track [Page 41] RFC 5804 ManageSieve July 2010

 Response Code: ENCRYPT-NEEDED
 Arguments (use ABNF to specify syntax, or the word NONE if none can
 be specified):  NONE
 Purpose:       This response code is returned in the NO response from
                an AUTHENTICATE command.  It indicates that site
                security policy requires the use of a strong
                encryption mechanism for the specified authentication
                identity and mechanism.
 Published Specification(s):  [RFC5804]
 Person & email address to contact for further information:
                Alexey Melnikov <alexey.melnikov@isode.com>
 Author/Change controller:  IESG.
 Response Code: QUOTA
 Arguments (use ABNF to specify syntax, or the word NONE if none can
 be specified):  NONE
 Purpose:       If this response code is returned in the NO/BYE
                response, it means that the command would have placed
                the user above the site-defined quota constraints.  If
                this response code is returned in the OK response, it
                can mean that the user is near its quota or that the
                user exceeded its quota, but the server supports soft
                quotas.
 Published Specification(s):  [RFC5804]
 Person & email address to contact for further information:
                Alexey Melnikov <alexey.melnikov@isode.com>
 Author/Change controller:  IESG.
 Response Code: QUOTA/MAXSCRIPTS
 Arguments (use ABNF to specify syntax, or the word NONE if none can
 be specified):  NONE
 Purpose:       If this response code is returned in the NO/BYE
                response, it means that the command would have placed
                the user above the site-defined limit on the number of
                Sieve scripts.  If this response code is returned in
                the OK response, it can mean that the user is near its
                quota or that the user exceeded its quota, but the
                server supports soft quotas.  This response code is a
                more specific version of the QUOTA response code.
 Published Specification(s):  [RFC5804]
 Person & email address to contact for further information:
                Alexey Melnikov <alexey.melnikov@isode.com>
 Author/Change controller:  IESG.

Melnikov & Martin Standards Track [Page 42] RFC 5804 ManageSieve July 2010

 Response Code: QUOTA/MAXSIZE
 Arguments (use ABNF to specify syntax, or the word NONE if none can
 be specified):  NONE
 Purpose:       If this response code is returned in the NO/BYE
                response, it means that the command would have placed
                the user above the site-defined maximum script size.
                If this response code is returned in the OK response,
                it can mean that the user is near its quota or that
                the user exceeded its quota, but the server supports
                soft quotas.  This response code is a more specific
                version of the QUOTA response code.
 Published Specification(s):  [RFC5804]
 Person & email address to contact for further information:
                Alexey Melnikov <alexey.melnikov@isode.com>
 Author/Change controller:  IESG.
 Response Code: REFERRAL
 Arguments (use ABNF to specify syntax, or the word NONE if none can
 be specified):  <sieveurl>
 Purpose:       This response code may be returned with a BYE result
                from any command, and includes a mandatory parameter
                that indicates what server to access to manage this
                user's Sieve scripts.  The server will be specified by
                a Sieve URL (see Section 3).  The scriptname portion
                of the URL MUST NOT be specified.  The client should
                authenticate to the specified server and use it for
                all further commands in the current session.
 Published Specification(s):  [RFC5804]
 Person & email address to contact for further information:
                Alexey Melnikov <alexey.melnikov@isode.com>
 Author/Change controller:  IESG.
 Response Code: SASL
 Arguments (use ABNF to specify syntax, or the word NONE if none can
 be specified):  <string>
 Purpose:       This response code can occur in the OK response to a
                successful AUTHENTICATE command and includes the
                optional final server response data from the server as
                specified by [SASL].
 Published Specification(s):  [RFC5804]
 Person & email address to contact for further information:
                Alexey Melnikov <alexey.melnikov@isode.com>
 Author/Change controller:  IESG.

Melnikov & Martin Standards Track [Page 43] RFC 5804 ManageSieve July 2010

 Response Code: TRANSITION-NEEDED
 Arguments (use ABNF to specify syntax, or the word NONE if none can
 be specified):  NONE
 Purpose:       This response code occurs in a NO response of an
                AUTHENTICATE command.  It indicates that the user name
                is valid, but the entry in the authentication database
                needs to be updated in order to permit authentication
                with the specified mechanism.  This is typically done
                by establishing a secure channel using TLS, followed
                by authenticating once using the [PLAIN]
                authentication mechanism.  The selected mechanism
                SHOULD then work for authentications in subsequent
                sessions.
 Published Specification(s):  [RFC5804]
 Person & email address to contact for further information:
                Alexey Melnikov <alexey.melnikov@isode.com>
 Author/Change controller:  IESG.
 Response Code: TRYLATER
 Arguments (use ABNF to specify syntax, or the word NONE if none can
 be specified):  NONE
 Purpose:       A command failed due to a temporary server failure.
                The client MAY continue using local information and
                try the command later.  This response code only make
                sense when returned in a NO/BYE response.
 Published Specification(s):  [RFC5804]
 Person & email address to contact for further information:
                Alexey Melnikov <alexey.melnikov@isode.com>
 Author/Change controller:  IESG.
 Response Code: ACTIVE
 Arguments (use ABNF to specify syntax, or the word NONE if none can
 be specified):  NONE
 Purpose:       A command failed because it is not allowed on the
                active script, for example, DELETESCRIPT on the active
                script.  This response code only makes sense when
                returned in a NO/BYE response.
 Published Specification(s):  [RFC5804]
 Person & email address to contact for further information:
                Alexey Melnikov <alexey.melnikov@isode.com>
 Author/Change controller:  IESG.

Melnikov & Martin Standards Track [Page 44] RFC 5804 ManageSieve July 2010

 Response Code: NONEXISTENT
 Arguments (use ABNF to specify syntax, or the word NONE if none can
 be specified):  NONE
 Purpose:       A command failed because the referenced script name
                doesn't exist.  This response code only makes sense
                when returned in a NO/BYE response.
 Published Specification(s):  [RFC5804]
 Person & email address to contact for further information:
                Alexey Melnikov <alexey.melnikov@isode.com>
 Author/Change controller:  IESG.
 Response Code: ALREADYEXISTS
 Arguments (use ABNF to specify syntax, or the word NONE if none can
 be specified):  NONE
 Purpose:       A command failed because the referenced script name
                already exists.  This response code only makes sense
                when returned in a NO/BYE response.
 Published Specification(s):  [RFC5804]
 Person & email address to contact for further information:
                Alexey Melnikov <alexey.melnikov@isode.com>
 Author/Change controller:  IESG.
 Response Code: WARNINGS
 Arguments (use ABNF to specify syntax, or the word NONE if none can
 be specified):  NONE
 Purpose:       This response code MAY be returned by the server in
                the OK response (but it might be returned with the NO/
                BYE response as well) and signals the client that even
                though the script is syntactically valid, it might
                contain errors not intended by the script writer.
 Published Specification(s):  [RFC5804]
 Person & email address to contact for further information:
                Alexey Melnikov <alexey.melnikov@isode.com>
 Author/Change controller:  IESG.
 Response Code: TAG
 Arguments (use ABNF to specify syntax, or the word NONE if none can
 be specified):  string
 Purpose:       This response code name is followed by a string
                specified in the command that caused this response.
                It is typically used for client state synchronization.
 Published Specification(s):  [RFC5804]
 Person & email address to contact for further information:
                Alexey Melnikov <alexey.melnikov@isode.com>
 Author/Change controller:  IESG.

Melnikov & Martin Standards Track [Page 45] RFC 5804 ManageSieve July 2010

7. Internationalization Considerations

 The LANGUAGE capability (see Section 1.7) allows a client to discover
 the current language used in all human-readable responses that might
 be returned at the end of any OK/NO/BYE response.  Human-readable
 text in OK responses typically doesn't need to be shown to the user,
 unless it is returned in response to a PUTSCRIPT or CHECKSCRIPT
 command that also contains the WARNINGS response code (Section 1.3).
 Human-readable text from NO/BYE responses is intended be shown to the
 user, unless the client can automatically handle failure of the
 command that caused such a response.  Clients SHOULD use response
 codes (Section 1.3) for automatic error handling.  Response codes MAY
 also be used by the client to present error messages in a language
 understood by the user, for example, if the LANGUAGE capability
 doesn't return a language understood by the user.
 Note that the human-readable text from OK (WARNINGS) or NO/BYE
 responses for PUTSCRIPT/CHECKSCRIPT commands is intended for advanced
 users that understand Sieve language.  Such advanced users are often
 sophisticated enough to be able to handle whatever language the
 server is using, even if it is not their preferred language, and will
 want to see error/warning text no matter what language the server
 puts it in.
 A client that generates Sieve script automatically, for example, if
 the script is generated without user intervention or from a UI that
 presents an abstract list of conditions and corresponding actions,
 SHOULD NOT present warning/error messages to the user, because the
 user might not even be aware that the client is using Sieve
 underneath.  However, if the client has a debugging mode, such
 warnings/errors SHOULD be available in the debugging mode.
 Note that this document doesn't provide a way to modify the currently
 used language.  It is expected that a future extension will address
 that.

8. Acknowledgements

 Thanks to Simon Josefsson, Larry Greenfield, Allen Johnson, Chris
 Newman, Lyndon Nerenberg, Tim Showalter, Sarah Robeson, Walter Wong,
 Barry Leiba, Arnt Gulbrandsen, Stephan Bosch, Ken Murchison, Phil
 Pennock, Ned Freed, Jeffrey Hutzelman, Mark E. Mallett, Dilyan
 Palauzov, Dave Cridland, Aaron Stone, Robert Burrell Donkin, Patrick
 Ben Koetter, Bjoern Hoehrmann, Martin Duerst, Pasi Eronen, Magnus
 Westerlund, Tim Polk, and Julien Coloos for help with this document.
 Special thank you to Phil Pennock for providing text for the NOOP
 command, as well as finding various bugs in the document.

Melnikov & Martin Standards Track [Page 46] RFC 5804 ManageSieve July 2010

9. References

9.1. Normative References

 [ABNF]         Crocker, D. and P. Overell, "Augmented BNF for Syntax
                Specifications: ABNF", STD 68, RFC 5234, January 2008.
 [ACAP]         Newman, C. and J. Myers, "ACAP -- Application
                Configuration Access Protocol", RFC 2244, November
                1997.
 [BASE64]       Josefsson, S., "The Base16, Base32, and Base64 Data
                Encodings", RFC 4648, October 2006.
 [DNS-SRV]      Gulbrandsen, A., Vixie, P., and L. Esibov, "A DNS RR
                for specifying the location of services (DNS SRV)",
                RFC 2782, February 2000.
 [KEYWORDS]     Bradner, S., "Key words for use in RFCs to Indicate
                Requirement Levels", BCP 14, RFC 2119, March 1997.
 [NET-UNICODE]  Klensin, J. and M. Padlipsky, "Unicode Format for
                Network Interchange", RFC 5198, March 2008.
 [NOTIFY]       Melnikov, A., Leiba, B., Segmuller, W., and T. Martin,
                "Sieve Email Filtering: Extension for Notifications",
                RFC 5435, January 2009.
 [RFC2277]      Alvestrand, H., "IETF Policy on Character Sets and
                Languages", BCP 18, RFC 2277, January 1998.
 [RFC2460]      Deering, S. and R. Hinden, "Internet Protocol, Version
                6 (IPv6) Specification", RFC 2460, December 1998.
 [RFC3490]      Faltstrom, P., Hoffman, P., and A. Costello,
                "Internationalizing Domain Names in Applications
                (IDNA)", RFC 3490, March 2003.
 [RFC4519]      Sciberras, A., "Lightweight Directory Access Protocol
                (LDAP): Schema for User Applications", RFC 4519, June
                2006.
 [RFC5646]      Phillips, A. and M. Davis, "Tags for Identifying
                Languages", BCP 47, RFC 5646, September 2009.
 [RFC791]       Postel, J., "Internet Protocol", STD 5, RFC 791,
                September 1981.

Melnikov & Martin Standards Track [Page 47] RFC 5804 ManageSieve July 2010

 [SASL]         Melnikov, A. and K. Zeilenga, "Simple Authentication
                and Security Layer (SASL)", RFC 4422, June 2006.
 [SASLprep]     Zeilenga, K., "SASLprep: Stringprep Profile for User
                Names and Passwords", RFC 4013, February 2005.
 [SCRAM]        Menon-Sen, A., Melnikov, A., Newman, C., and N.
                Williams, "Salted Challenge Response Authentication
                Mechanism (SCRAM) SASL and GSS-API Mechanisms", RFC
                5802, July 2010.
 [SIEVE]        Guenther, P. and T. Showalter, "Sieve: An Email
                Filtering Language", RFC 5228, January 2008.
 [StringPrep]   Hoffman, P. and M. Blanchet, "Preparation of
                Internationalized Strings ("stringprep")", RFC 3454,
                December 2002.
 [TLS]          Dierks, T. and E. Rescorla, "The Transport Layer
                Security (TLS) Protocol Version 1.2", RFC 5246, August
                2008.
 [URI-GEN]      Berners-Lee, T., Fielding, R., and L. Masinter,
                "Uniform Resource Identifier (URI): Generic Syntax",
                STD 66, RFC 3986, January 2005.
 [UTF-8]        Yergeau, F., "UTF-8, a transformation format of ISO
                10646", STD 63, RFC 3629, November 2003.
 [X509]         Cooper, D., Santesson, S., Farrell, S., Boeyen, S.,
                Housley, R., and W. Polk, "Internet X.509 Public Key
                Infrastructure Certificate and Certificate Revocation
                List (CRL) Profile", RFC 5280, May 2008.
 [X509-SRV]     Santesson, S., "Internet X.509 Public Key
                Infrastructure Subject Alternative Name for Expression
                of Service Name", RFC 4985, August 2007.

9.2. Informative References

 [DIGEST-MD5]   Leach, P. and C. Newman, "Using Digest Authentication
                as a SASL Mechanism", RFC 2831, May 2000.
 [GSSAPI]       Melnikov, A., "The Kerberos V5 ("GSSAPI") Simple
                Authentication and Security Layer (SASL) Mechanism",
                RFC 4752, November 2006.

Melnikov & Martin Standards Track [Page 48] RFC 5804 ManageSieve July 2010

 [I-HAVE]       Freed, N., "Sieve Email Filtering: Ihave Extension",
                RFC 5463, March 2009.
 [IMAP]         Crispin, M., "INTERNET MESSAGE ACCESS PROTOCOL -
                VERSION 4rev1", RFC 3501, March 2003.
 [LDAP]         Zeilenga, K., "Lightweight Directory Access Protocol
                (LDAP): Technical Specification Road Map", RFC 4510,
                June 2006.
 [PLAIN]        Zeilenga, K., "The PLAIN Simple Authentication and
                Security Layer (SASL) Mechanism", RFC 4616, August
                2006.

Authors' Addresses

 Alexey Melnikov (editor)
 Isode Limited
 5 Castle Business Village
 36 Station Road
 Hampton, Middlesex  TW12 2BX
 UK
 EMail: Alexey.Melnikov@isode.com
 Tim Martin
 BeThereBeSquare, Inc.
 672 Haight st.
 San Francisco, CA  94117
 USA
 Phone: +1 510 260-4175
 EMail: timmartin@alumni.cmu.edu

Melnikov & Martin Standards Track [Page 49]

/data/webs/external/dokuwiki/data/pages/rfc/rfc5804.txt · Last modified: 2010/07/13 04:03 (external edit)