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rfc:rfc5703

Network Working Group T. Hansen Request for Comments: 5703 AT&T Laboratories Category: Standards Track C. Daboo

                                                            Apple Inc.
                                                          October 2009
   Sieve Email Filtering: MIME Part Tests, Iteration, Extraction,
                     Replacement, and Enclosure

Abstract

 This document defines extensions to the Sieve email filtering
 language to permit analysis and manipulation of the MIME body parts
 of an email message.

Status of This Memo

 This document specifies an Internet standards track protocol for the
 Internet community, and requests discussion and suggestions for
 improvements.  Please refer to the current edition of the "Internet
 Official Protocol Standards" (STD 1) for the standardization state
 and status of this protocol.  Distribution of this memo is unlimited.

Copyright Notice

 Copyright (c) 2009 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 BSD License.
 This document may contain material from IETF Documents or IETF
 Contributions published or made publicly available before November
 10, 2008.  The person(s) controlling the copyright in some of this
 material may not have granted the IETF Trust the right to allow
 modifications of such material outside the IETF Standards Process.
 Without obtaining an adequate license from the person(s) controlling
 the copyright in such materials, this document may not be modified

Hansen & Daboo Standards Track [Page 1] RFC 5703 Sieve MIME Operations October 2009

 outside the IETF Standards Process, and derivative works of it may
 not be created outside the IETF Standards Process, except to format
 it for publication as an RFC or to translate it into languages other
 than English.

Table of Contents

 1. Introduction ....................................................2
 2. Conventions Used in This Document ...............................3
 3. Sieve Loops: Actions "foreverypart" and "break" .................3
 4. Changes to Sieve Tests ..........................................4
    4.1. Test "header" ..............................................4
    4.2. Test "address" .............................................7
    4.3. Test "exists" ..............................................8
 5. Action "replace" ................................................8
 6. Action "enclose" ...............................................10
 7. Action "extracttext" ...........................................11
 8. Sieve Capability Strings .......................................11
 9. Examples .......................................................12
    9.1. Example 1 .................................................12
    9.2. Example 2 .................................................12
    9.3. Example 3 .................................................13
 10. Acknowledgements ..............................................13
 11. Security Considerations .......................................14
 12. IANA Considerations ...........................................14
    12.1. foreverypart capability ..................................15
    12.2. mime capability ..........................................15
    12.3. replace capability .......................................15
    12.4. enclose capability .......................................16
    12.5. extracttext capability ...................................16
 13. References ....................................................16
    13.1. Normative References .....................................16
    13.2. Informative References ...................................17

1. Introduction

 MIME messages ([RFC2045]) are often complex objects, consisting of
 many parts and sub-parts.  This Sieve ([RFC5228]) extension defines
 mechanisms for performing tests on MIME body parts, looping through
 the MIME body parts, extracting information from a MIME body part,
 changing the contents of a MIME body part, and enclosing the entire
 message within a wrapper.

Hansen & Daboo Standards Track [Page 2] RFC 5703 Sieve MIME Operations October 2009

2. Conventions Used in This Document

 Conventions for notations are as in [RFC5228], Section 1.1.
 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 [RFC2119].

3. Sieve Loops: Actions "foreverypart" and "break"

 The base Sieve language has no looping mechanism.  Given that
 messages may contain multiple parts, in order to support filters that
 apply to any and all parts, we introduce a new control command:
 "foreverypart", which is an iterator that walks though every MIME
 part of a message, including nested parts, depth first, and applies
 the commands in the specified block to each of them.  The iterator
 will start with the first MIME part (as its current context) and will
 execute a command block (Sieve commands enclosed by {...}).  Upon
 completion of this command block, the iterator advances to the next
 MIME part (as its current context) and executes the same command
 block again.
 The iterator can be terminated prematurely by a new Sieve control
 command, "break".
 Usage:  foreverypart [":name" string] block
 Usage:  break [":name" string];
 "foreverypart" commands can be nested inside other "foreverypart"
 commands.  When this occurs, the nested "foreverypart" iterates over
 the MIME parts contained within the MIME part currently being
 targeted by the nearest enclosing "foreverypart" command.  (That is,
 the inner loop only operates on children of the bodypart currently
 accessed by the outer loop.)  If that MIME part is a terminal MIME
 part (i.e., does not contain other MIME parts), then the nested
 "foreverypart" loop is simply ignored.
 Sieve implementations MAY limit the number of nested loops that occur
 within one another; however, they MUST support at least one nested
 loop inside another loop.
 If a name is given to a "break" command, it terminates the closest
 enclosing loop with the identical matching name.  (If a nested
 "foreverypart" name is the same as a "foreverypart" name in an outer
 level, the outer level name is hidden.)  It is an error if there is
 no enclosing loop with that name.

Hansen & Daboo Standards Track [Page 3] RFC 5703 Sieve MIME Operations October 2009

 If no name is given in a "break" command (i.e., the ":name" parameter
 is omitted), the break command terminates the closest enclosing loop.

4. Changes to Sieve Tests

 This specification extends the base Sieve "header", "address", and
 "exists" tests to support targeting those tests at a specific MIME
 part or at all MIME parts in the enclosing scope.

4.1. Test "header"

 The "header" test is extended with the addition of new ":mime" and
 ":anychild" tagged arguments and their associated options.
 Usage:  header [":mime"] [":anychild"] [MIMEOPTS]
    [COMPARATOR] [MATCH-TYPE]
    <header-names: string-list> <key-list: string-list>
    The definition of [MIMEOPTS] is:
 Syntax:  ":type" / ":subtype" / ":contenttype" /
    ":param" <param-list: string-list>
 When the ":mime" tagged argument is present in the "header" test, it
 will parse the MIME header lines in the message so that tests can be
 performed on specific elements.  The ":anychild" tagged argument may
 only appear when the ":mime" tagged argument is present, and only
 modifies the semantics of the ":mime" tagged argument.  That is,
 presence of the ":anychild" in absence of ":mime" is an error.
 When used outside the context of a "foreverypart" iterator, and
 without an ":anychild" tagged argument, the "header" test will
 examine only the outer top-level [RFC5322] headers of the message.
 When used inside the context of a "foreverypart" iterator, and
 without an ":anychild" tagged argument, the "header" test will
 examine the headers associated with the current MIME part context
 from the loop.
 When used outside the context of a "foreverypart" iterator, and with
 an ":anychild" tagged argument, the "header" test will examine all
 MIME body parts and return true if any of them satisfies the test.
 When used inside the context of a "foreverypart" iterator, and with
 an ":anychild" tagged argument, the "header" test will examine the
 current MIME part context and all its nested MIME body parts,
 returning true if any of them satisfies the test.

Hansen & Daboo Standards Track [Page 4] RFC 5703 Sieve MIME Operations October 2009

 The "header" test with the ":mime" tagged argument can test various
 aspects of certain structured MIME headers.  Implementations SHOULD
 support desegmentation, decoding, and charset translation of
 parameter values encoded according to [RFC2231] as part of this test.
 Additionally, [RFC2047] describes a process whereby [RFC5322] headers
 can be encoded in various ways.  That encoding is not strictly
 allowed in MIME parameters; however, in practice, it has been used in
 many email implementations.  So, Sieve implementations MAY decode
 [RFC2047]-encoded words in parameter values as part of this test.
 These options are available:
 :type          for a "Content-Type" MIME header field, parses and
                tests the value of the MIME type specified in the
                header; for a "Content-Disposition" MIME header field,
                parses and tests the value of the disposition
                specified in the header; for other MIME headers, uses
                a blank string for the test.
 :subtype       for a "Content-Type" MIME header field, parses and
                tests the value of the MIME subtype specified in the
                header; for a "Content-Disposition" MIME header field,
                uses a blank string for the test; for other MIME
                headers, uses a blank string for the test.
 :contenttype   for a "Content-Type" MIME header field, parses and
                tests the combined value of the MIME type and subtype
                specified in the header; for a "Content-Disposition"
                MIME header field, behaves the same as the ":type"
                option; for other MIME headers, uses a blank string
                for the test.
 :param         parses the header looking for MIME parameters in the
                header.  The supplied string-list lists the names of
                any parameters to be tested.  If any one named
                parameter value matches any of the test string values,
                the test will return true.
 When the ":count" option from [RFC5231] is used, the following
 applies:
 a.  for ":type", ":subtype", or ":contenttype", return a count of the
     number of headers that parsed successfully
 b.  for ":param", return a count of the number of parameters with the
     given name that were found

Hansen & Daboo Standards Track [Page 5] RFC 5703 Sieve MIME Operations October 2009

 Example:
 require ["mime", "fileinto"];
 if header :mime :type "Content-Type" "image"
 {
     fileinto "INBOX.images";
 }
 In this example, any message that contains a MIME image type part at
 the top-level is saved to the mailbox "INBOX.images".
 Example:
 require ["mime", "fileinto"];
 if header :mime :anychild :contenttype
           "Content-Type" "text/html"
 {
     fileinto "INBOX.html";
 }
 In this example, any message that contains any MIME part with a
 content-type of "text/html" is saved to the mailbox "INBOX.html".
 Example:
 require ["mime", "foreverypart", "fileinto"];
 foreverypart
 {
     if allof (
       header :mime :param "filename" :contains
          "Content-Disposition" "important",
       header :mime :subtype "Content-Type" "pdf",
       size :over "100K")
     {
         fileinto "INBOX.important";
         break;
     }
 }
 In this example, any message that contains a MIME part that has a
 content-disposition with a filename parameter containing the text
 "important", has a content-subtype of "pdf" and is bigger than 100 Kb
 is saved to the mailbox "INBOX.important".

Hansen & Daboo Standards Track [Page 6] RFC 5703 Sieve MIME Operations October 2009

4.2. Test "address"

 The "address" test is extended with the addition of new ":mime" and
 ":anychild" tagged arguments and their associated options.
 Usage:  address [":mime"] [":anychild"] [COMPARATOR]
    [ADDRESS-PART] [MATCH-TYPE]
    <header-list: string-list> <key-list: string-list>
 When the ":mime" tagged argument is present in the "address" test, it
 will parse the MIME header lines as if they were standard address
 header lines in a message so that tests can be performed on specific
 elements.
 The behavior of the ":anychild" tagged argument and the interaction
 with the "foreverypart" iterator is the same as for the extended
 "header" test in Section 4.1.
 That is,
    the use of "address" when both the ":mime" and ":anychild" tagged
    arguments are omitted is the test defined in [RFC5228], i.e., it
    will *only* operate on top-level header fields, whether or not it
    is inside "foreverypart".
    the use of "address" with ":mime" and no ":anychild" operates on
    the current MIME part only (or on the top-level header fields, if
    outside "foreverypart").
    the use of "address" with ":mime" and ":anychild" operates on the
    current MIME part and all of its descendants.
 Example:
 require ["mime", "fileinto"];
 if address :mime :is :all "content-from" "tim@example.com"
 {
     fileinto "INBOX.part-from-tim";
 }
 In this example, any message that contains a MIME Content-From header
 at the top-level matching the text "tim@example.com" is saved to the
 mailbox "INBOX.part-from-tim".

Hansen & Daboo Standards Track [Page 7] RFC 5703 Sieve MIME Operations October 2009

4.3. Test "exists"

 The "exists" test is extended with the addition of the new ":mime"
 and ":anychild" tagged arguments and their associated options.
 Usage:  exists [":mime"] [":anychild"] <header-names: string-list>
 When the ":mime" tagged argument is present in the "exists" test, the
 test is extended to check for the existence of MIME headers in MIME
 parts.
 The behavior of the ":anychild" tagged argument and the interaction
 with the "foreverypart" iterator is the same as for the extended
 "header" test Section 4.1.
 That is,
    the use of "exists" when both the ":mime" and ":anychild" tagged
    arguments are omitted is the test defined in [RFC5228], i.e., it
    will *only* operate on top-level header fields, whether or not it
    is inside "foreverypart".
    the use of "exists" with ":mime" and no ":anychild" operates on
    the current MIME part only (or on the top-level header fields, if
    outside "foreverypart").
    the use of "exists" with ":mime" and ":anychild" operates on the
    current MIME part and all of its descendants.
 Example:
 require ["mime", "fileinto"];
 if exists :mime :anychild "content-md5"
 {
     fileinto "INBOX.md5";
 }
 In this example, any message that contains a MIME Content-MD5 header
 in any MIME part is saved to the mailbox "INBOX.md5".

5. Action "replace"

 Usage:  replace [":mime"] [":subject" string] [":from" string]
    <replacement: string>
 The "replace" command is defined to allow a MIME part to be replaced
 with the text supplied in the command.

Hansen & Daboo Standards Track [Page 8] RFC 5703 Sieve MIME Operations October 2009

 When used in the context of a "foreverypart" iterator, the MIME part
 to be replaced is the "current" MIME part.  If the current MIME
 context is a multipart MIME part, the entire multipart MIME part is
 replaced, which would alter the MIME structure of the message by
 eliminating all of the children of the multipart part.  (Replacing a
 non-multipart MIME part within a "foreverypart" loop context does not
 alter the overall message structure.)  If the MIME structure is
 altered, the change takes effect immediately: the "foreverypart"
 iterator that is executing does not go into the no-longer existing
 body parts, and subsequent "foreverypart" iterators would use the new
 message structure.
 When used outside the context of a "foreverypart" loop, the MIME part
 to be replaced is the entire message.
 If the ":mime" parameter is not specified, the replacement string is
 a text/plain part in UTF-8 [RFC3629].
 If the ":mime" parameter is specified, then the replacement string
 is, in fact, a MIME entity as defined in [RFC2045], Section 2.4,
 including both MIME headers and content.
 If the entire message is being replaced, the optional ":subject"
 parameter specifies a subject line to attach to the message that is
 generated.  UTF-8 characters can be used in the string argument;
 implementations MUST convert the string to [RFC2047]-encoded words if
 and only if non-ASCII characters are present.  If the ":subject"
 parameter is used, implementations MUST preserve any previous Subject
 header as an Original-Subject header.  Implementations MUST preserve
 all other header fields from the original message with the exception
 of those relating to the MIME structure that is being replaced.
 If the entire message is being replaced, as an indication that the
 message is no longer as created by the original author of the
 message, the optional ":from" parameter may be used to specify an
 alternate address to use in the From field of the message that is
 generated.  The string must specify a valid [RFC5322] mailbox-list.
 Implementations SHOULD check the syntax and generate an error when a
 syntactically invalid ":from" parameter is specified.
 Implementations MAY also impose restrictions on what addresses can be
 specified in a ":from" parameter; it is suggested that values that
 fail such a validity check simply be ignored rather than causing the
 "replace" action to fail.  If the From header is changed,
 implementations MUST preserve the previous From header as an
 Original-From header.

Hansen & Daboo Standards Track [Page 9] RFC 5703 Sieve MIME Operations October 2009

 Implementations that support the "editheader" extension [RFC5293]
 MUST ensure that any Original-Subject or Original-From headers added
 by the system cannot be modified or removed.  Implementations MAY
 prevent the addition of Original-Subject and Orignal-From headers via
 the "editheader" extension.
 If ":mime" is specified and either ":subject" or ":from" is
 specified, the ":subject:" or ":from" parameter MUST be ignored.
 This SHOULD be flagged as a compilation error.

6. Action "enclose"

 Usage:  enclose <:subject string> <:headers string-list> string
 A new Sieve action command is defined to allow an entire message to
 be enclosed as an attachment to a new message.  After enclosure,
 subsequent actions affecting the message header or content, as well
 as tests operating on the MIME structure or accessing MIME header
 fields, use the newly created message instead of the original
 message; this means that any use of a "replace" action or other
 similar actions should be executed before the "enclose" action.
 If multiple "enclose" actions are executed by a script, the message
 is enclosed multiple times.  (If a Sieve script desires to choose
 between different enclosures, or wants to delay the enclosure to the
 end of the script, it can use variables with appropriate tests
 [RFC5229].)
 This action does not affect messages that are forwarded via a
 "redirect" action.
 Specifically, the original message becomes a multipart/mixed message
 with two parts: a text/plain portion with the string argument as its
 body, and a message/rfc822 portion with the original message
 enclosed.  The Content-Type: header field becomes multipart/mixed.
 The optional Subject: header is specified by the ":subject" argument;
 if not present, the subject will be taken from the enclosed message.
 Any headers specified by ":headers" are copied from the old message
 into the new message.  If not specified by ":headers", Date: and
 From: headers should be synthesized to reflect the current date and
 the user running the Sieve action.

Hansen & Daboo Standards Track [Page 10] RFC 5703 Sieve MIME Operations October 2009

7. Action "extracttext"

 Usage:  extracttext [MODIFIER] [":first" number] <varname: string>
 The "extracttext" action may be used within the context of a
 "foreverypart" loop and is used to store text into a variable as
 defined by [RFC5229].  Servers MUST support transcoding of any
 textual body part into UTF-8 for use with this action.  This requires
 decoding any transfer encoding as well as transcoding from the
 indicated character set into UTF-8.  It stores at most ":first"
 characters of the transcoded content of the current MIME body part in
 the variable identified by varname.  If the ":first" parameter is not
 present, the whole content of the current MIME body part is stored.
 In either case, the actually stored data MAY be truncated to conform
 to implementation specific limit on variable length and/or on MIME
 body part length.  If the transfer encoding or character set is
 unrecognized by the implementation or recognized but invalid, an
 empty string will result.
 If "extracttext" is used outside the context of a "foreverypart"
 loop, the action will set the variable identified by varname to the
 empty string.  This SHOULD be flagged as a compilation error.
 Modifiers are applied on the extracted text before it is stored in
 the variable.

8. Sieve Capability Strings

 A Sieve implementation that defines the "foreverypart" and "break"
 actions will advertise the capability string "foreverypart".
 A Sieve implementation that defines the ":mime" and ":anychild"
 tagged arguments to the "header", "address", and "exists" commands
 will advertise the capability string "mime".
 A Sieve implementation that defines the "replace" action will
 advertise the capability string "replace".
 A Sieve implementation that defines the "enclose" action will
 advertise the capability string "enclose".
 A Sieve implementation that defines the "extracttext" action will
 advertise the capability string "extracttext".  Note that to be
 useful, the "extracttext" action also requires the "variables"
 [RFC5229] and "foreverypart" capabilities.

Hansen & Daboo Standards Track [Page 11] RFC 5703 Sieve MIME Operations October 2009

9. Examples

9.1. Example 1

 Consider a Sieve script to replace some of the Windows executable
 attachments in a message.  (The actual list of executable types and
 extensions is considerably longer and constantly changing.  The tests
 shown here are an example only.)  Such a script might look like this:
 require [ "foreverypart", "mime", "replace" ];
 foreverypart
 {
   if anyof (
          header :mime :contenttype :is
            "Content-Type" "application/exe",
          header :mime :param "filename"
            :matches ["Content-Type", "Content-Disposition"] "*.com" )
   {
     replace "Executable attachment removed by user filter";
   }
 }

9.2. Example 2

 Consider a Sieve script to warn the user about some of the executable
 attachment types.  (The actual list of executable types and
 extensions is considerably longer and constantly changing.  The tests
 shown here are an example only.)  Such a script might look like this:
 require [ "foreverypart", "mime", "enclose" ];
 foreverypart
 {
   if header :mime :param "filename"
      :matches ["Content-Type", "Content-Disposition"]
        ["*.com", "*.exe", "*.vbs", "*.scr",
         "*.pif", "*.hta", "*.bat", "*.zip" ]
   {
     # these attachment types are executable
     enclose :subject "Warning" :text
 WARNING! The enclosed message contains executable attachments.
 These attachment types may contain a computer virus program
 that can infect your computer and potentially damage your data.
 Before clicking on these message attachments, you should verify
 with the sender that this message was sent by them and not a
 computer virus.

Hansen & Daboo Standards Track [Page 12] RFC 5703 Sieve MIME Operations October 2009

 .
 ;
     break;
   }
 }

9.3. Example 3

 A Sieve script to extract subject and text out of messages from the
 boss might look like this:
 require ["mime", "variables", "extracttext"];
 if header :contains "from" "boss@example.org"
 {
   # :matches is used to get the value of the Subject header
   if header :matches "Subject" "*"
   {
     set "subject" "${1}";
   }
   # extract the first 100 characters of the first text/* part
   foreverypart
   {
     if header :mime :type :is "Content-Type" "text"
     {
       extracttext :first 100 "msgcontent";
       break;
     }
   }
   # if it's not a 'for your information' message
   if not header :contains "subject" "FYI:"
   {
     # do something using ${subject} and ${msgcontent}
     # such as sending a notification using a
     # notification extension
   }
 }

10. Acknowledgements

 Comments from members of the MTA Filters Working Group, in particular
 Ned Freed, Kjetil Torgrim Homme, Mark Mallett, Alexey Melnikov, Aaron
 Stone, and Nigel Swinson are gratefully acknowledged.

Hansen & Daboo Standards Track [Page 13] RFC 5703 Sieve MIME Operations October 2009

11. Security Considerations

 The "enclose" action creates an entirely new message, as compared to
 just redirecting or forwarding the existing message.  Therefore, any
 site policies applicable to message submission should be enforced.
 The looping specification specified here provides easier access to
 information about the message contents, which may also be achieved
 through other sieve tests.  This is not believed to raise any
 additional security issues beyond those for the Sieve "envelope" and
 "body" [RFC5173] tests.
 Any change in message content may interfere with digital signature
 mechanisms that include that content in the signed material.  In
 particular, using "replace" makes direct changes to the body content
 and will affect the body hash included in Domain Keys Identified Mail
 (DKIM) signatures [RFC4871], or the message signature used for Secure
 MIME (S/MIME) [RFC3851], Pretty Good Privacy (PGP) [RFC1991] or
 OpenPGP [RFC4880].
 It is not possible to examine the MIME structure of decrypted content
 in a multipart/encrypted MIME part.
 When "enclose" is used on a message containing a multipart/signed
 MIME part, the Sieve implementation MUST ensure that the original
 message is copied octet-for-octet to maintain the validity of the
 digital signature.
 The system MUST be sized and restricted in such a manner that even
 malicious use of MIME part matching does not deny service to other
 users of the host system.
 All of the security considerations given in the base Sieve
 specification also apply to these extensions.

12. IANA Considerations

 The Original-Subject and Original-From headers have been registered
 in the Permanent Message Header Fields registry.
 The following templates specify the IANA registrations of the Sieve
 extensions specified in this document.  This information has been
 added to the IANA registry of Sieve Extensions (currently found at
 http://www.iana.org).

Hansen & Daboo Standards Track [Page 14] RFC 5703 Sieve MIME Operations October 2009

12.1. foreverypart capability

 To: iana@iana.org
 Subject: Registration of new Sieve extension
 Capability name: foreverypart
 Description: adds the "foreverypart" and "break" actions for
 iterating through MIME parts of a message.
 RFC number: RFC 5703
 Contact address: The Sieve discussion list
 <ietf-mta-filters@imc.org>.

12.2. mime capability

 To: iana@iana.org
 Subject: Registration of new Sieve extension
 Capability name: mime
 Description: adds the ":mime" and ":anychild" tagged arguments to the
 "header", "address", and "exists" tests.  Adds the ":type",
 ":subtype", ":contenttype", and ":param" options when ":mime" is used
 with the "header" test.
 RFC number: RFC 5703
 Contact address: The Sieve discussion list
 <ietf-mta-filters@imc.org>.

12.3. replace capability

 To: iana@iana.org
 Subject: Registration of new Sieve extension
 Capability name: replace
 Description: adds the "replace" action for replacing a MIME body part
 of a message.
 RFC number: RFC 5703
 Contact address: The Sieve discussion list
 <ietf-mta-filters@imc.org>.

Hansen & Daboo Standards Track [Page 15] RFC 5703 Sieve MIME Operations October 2009

12.4. enclose capability

 To: iana@iana.org
 Subject: Registration of new Sieve extension
 Capability name: enclose
 Description: adds the "enclose" action for enclosing a message with a
 wrapper.
 RFC number: RFC 5703
 Contact address: The Sieve discussion list
 <ietf-mta-filters@imc.org>.

12.5. extracttext capability

 To: iana@iana.org
 Subject: Registration of new Sieve extension
 Capability name: extracttext
 Description: adds the "extracttext" action for extracting text from a
 MIME body part.
 RFC number: RFC 5703
 Contact address: The Sieve discussion list
 <ietf-mta-filters@imc.org>.

13. References

13.1. Normative References

 [RFC2045]  Freed, N. and N. Borenstein, "Multipurpose Internet Mail
            Extensions (MIME) Part One: Format of Internet Message
            Bodies", RFC 2045, November 1996.
 [RFC2047]  Moore, K., "MIME (Multipurpose Internet Mail Extensions)
            Part Three: Message Header Extensions for Non-ASCII Text",
            RFC 2047, November 1996.
 [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
            Requirement Levels", BCP 14, RFC 2119, March 1997.
 [RFC2231]  Freed, N. and K. Moore, "MIME Parameter Value and Encoded
            Word Extensions:
            Character Sets, Languages, and Continuations", RFC 2231,
            November 1997.

Hansen & Daboo Standards Track [Page 16] RFC 5703 Sieve MIME Operations October 2009

 [RFC3629]  Yergeau, F., "UTF-8, a transformation format of ISO
            10646", STD 63, RFC 3629, November 2003.
 [RFC5173]  Degener, J. and P. Guenther, "Sieve Email Filtering: Body
            Extension", RFC 5173, April 2008.
 [RFC5228]  Guenther, P. and T. Showalter, "Sieve: An Email Filtering
            Language", RFC 5228, January 2008.
 [RFC5229]  Homme, K., "Sieve Email Filtering: Variables Extension",
            RFC 5229, January 2008.
 [RFC5231]  Segmuller, W. and B. Leiba, "Sieve Email Filtering:
            Relational Extension", RFC 5231, January 2008.
 [RFC5293]  Degener, J. and P. Guenther, "Sieve Email Filtering:
            Editheader Extension", RFC 5293, August 2008.
 [RFC5322]  Resnick, P., Ed., "Internet Message Format", RFC 5322,
            October 2008.

13.2. Informative References

 [RFC1991]  Atkins, D., Stallings, W., and P. Zimmermann, "PGP Message
            Exchange Formats", RFC 1991, August 1996.
 [RFC3851]  Ramsdell, B., "Secure/Multipurpose Internet Mail
            Extensions (S/MIME) Version 3.1 Message Specification",
            RFC 3851, July 2004.
 [RFC4871]  Allman, E., Callas, J., Delany, M., Libbey, M., Fenton,
            J., and M. Thomas, "DomainKeys Identified Mail (DKIM)
            Signatures", RFC 4871, May 2007.
 [RFC4880]  Callas, J., Donnerhacke, L., Finney, H., Shaw, D., and R.
            Thayer, "OpenPGP Message Format", RFC 4880, November 2007.

Hansen & Daboo Standards Track [Page 17] RFC 5703 Sieve MIME Operations October 2009

Authors' Addresses

 Tony Hansen
 AT&T Laboratories
 200 Laurel Ave.
 Middletown, NJ  07748
 USA
 EMail: tony+sieveloop@maillennium.att.com
 Cyrus Daboo
 Apple Inc.
 1 Infinite Loop
 Cupertino, CA  95014
 USA
 EMail: cyrus@daboo.name
 URI:   http://www.apple.com/

Hansen & Daboo Standards Track [Page 18]

/data/webs/external/dokuwiki/data/pages/rfc/rfc5703.txt · Last modified: 2009/10/28 00:03 (external edit)