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rfc:rfc524

Network Working Group J. White Request for Comments: 524 SRI-ARC NIC: 17140 13 June 1973

                       A Proposed Mail Protocol

AUTHOR'S INTENT

 This is the document I offered in (15146,) to write.  It's a proposed
 specification for handling mail in the Network -- a Mail Protocol.
 Main handling is currently implemented as two FTP commands, MAIL and
 MLFL, which permit an FTP user process to deliver a file or string of
 text to an FTP server process, designating it as mail to be made
 available to a user, identified by a local name, in its host.  The
 protocol proposed here is much richer than that, both in terms of the
 functions it supports, and in terms of the flexibility it provides.
 Although one can (I think) and might, implement software on the basis
 of this document, this REALLY IS a Request for Comments.  Comments,
 questions, position papers are solicited.  There are, I'm sure, bugs
 in the protocol specified here, and I hope that readers will point
 them out via RFC as they discover them.
 Various members of the Network community have, during the last few
 months, pointed out to me specific inadequacies in the existing mail
 commands and asked me to be conscious of them in designing a new
 protocol.  I've tried to do that.  If anyone feels that his concern
 wasn't properly dealt with here, or that it slipped through the
 cracks entirely (for which I apologize in advance), I would
 appreciate it if he would prod me once more.

INTRODUCTION

 THE MAIL PROTOCOL ENVIRONMENT
    The Mail Protocol (MP) is implemented by Mail user and server
    processes, in keeping with the model for previous high-level
    protocols.  The Mail user and server processes are further
    specified to be also FTP user and server processes, respectively.
    That is, MP is implemented as a set of commands accessible from
    within the FTP command space.
    The MP command set is defined to lie conceptually within a
    subsystem, invoked from the FTP command space with the command
    MAIL <CFLF>.

White [Page 1] RFC 524 A Proposed Mail Protocol 13 June 1973

       NOTE:  Since a command called 'MAIL' already exists within the
       FTP command space, the command name 'XMAIL' might substitute
       for 'MAIL' while the current mail commands are being phased
       out.
    The MP command set may or may not (according to the implementation
    of a particular server) be implemented by a process distinct from
    that which implements FTP proper.
    The following are implications of the 'subsystem' concept, of
    which the reader (and implementer) must be aware:
       (1) Names of MP commands are known only within the MP
       subsystem.  MP commands must (and should naturally) be rejected
       by the server if the user process presents them outside of the
       subsystem.
       (2) Exit from the Mail subsystem (to the FTP command space) is
       effected with and only with the command EXIT <CRLF>.  FTP
       commands must be rejected by the server if the user presents
       them while inside the subsystem (i.e., before EXIT is issued).
       (3) The same command name may be assigned without ambiguity to
       two entirely different commands, provided that one lies within
       the FTP command space and the other within MP, the two being
       distinguishable by their contexts.  MP and FTP therefore do not
       compete for command names, and MP command names may be chosen
       without regard for the environment in which the subsystem
       resides.
       NOTE:  It so happens that there are commands DEFINED within MP
       which duplicate the functions of FTP commands and bear the same
       names.  The effective result is that some commands are
       explicitly allowed within MP.  The reader will understand that
       this fact is consistent with the conventions described in 1-3
       above, and that no ambiguities result.
    The subsystem concept (if not the name 'subsystem') is taken from
    Mike Padlipsky's Unified User Level Protocol (UULP), which the
    author of the present document strongly supports.  The fact that
    MP is accessed from FTP, rather than both FTP and MP being
    accessed independently from a more general executive program, is
    simply a concession to the fact that FTP is widely implemented and
    UULP isn't.  The author hopes that protocol development will, in
    the near future, begin to proceed along the lines exemplified by
    UULP.

White [Page 2] RFC 524 A Proposed Mail Protocol 13 June 1973

    MP conforms to FTP in general syntax.  In particular, commands and
    their responses are strings of NVT characters; command names are
    limited to four or fewer, upper- or lower-case, alphameric
    characters, and are terminated by the character SP; commands are
    generally terminated with the TELNET New Line sequence (CR LF);
    command responses contain both numeric (process readable) and text
    (human readable) portions.  Both reader and implementer are
    referred to the FTP protocol document for a detailed description
    of such matters; no attempt has been made to duplicate the
    discussion in the present document.
    The FTP protocol document assigns those replies whose second digit
    is '6' to RJE functions.  In like manner MP appropriates those
    reply codes whose second digit is '7' for reporting results
    peculiar to its functions.  It is, however, the author's position
    that FTP, MP, and the RJE protocol are all best implemented as
    subsystems under a common UULP executive, in which case a single
    subset of the reply space could be used unambiguously by all three
    protocols (and any yet to be defined), since every reply would
    implicitly be qualified by the name of the subsystem from which it
    emanates.
 THE MAIL MODEL
    MP defines mail to be text communicated between users (both human
    and processes) in less that (but ideally approaching) real time.
    The definition excludes so-called console-to-console
    communication, where users exchange information at the character
    or line level.
    Pieces of mail are characterized by such attributes as title,
    content, author, and recipient.  A piece of mail may be a one- or
    two-line message sent from one individual to another, a draft of a
    document sent by one individual to a design group for review, a
    polished, formal document sent from one group to another, a
    message sent to a human user by a process (e.g., an RJE server
    process might notify a user by Network Mail when his job has
    completed), etc.  All such forms of communication are mail and are
    supported by MP.
    Pieces of mail can be forwarded from one location to another
    Pieces of mail can be replied to.
    The identity of the author of a piece of mail can be verified,
    avoiding forgery and misrepresentation.

White [Page 3] RFC 524 A Proposed Mail Protocol 13 June 1973

    Pieces of mail can be permanently recorded, assigned a long-term
    identifier by which they can be forever be retrieved for
    reference, and entered in catalogs.  And access to such recorded
    mail can be restricted to a specified subset of the user
    community.
    Some hosts accept mail whose recipients reside elsewhere in the
    Network, and assume responsibility for delivering the mail to them
    (worrying about retrying delivery when hosts are down, etc.), and
    acknowledging its delivery to the sender.
    The picture being painted for the reader is one in which processes
    cooperate in various ways to flexibly move and manage Network
    mail.  The author claims (without proof, of course) that the
    picture will in the future get yet more complicated, but that the
    proposal specified here can be conveniently enlarged to handle
    that picture too.

ORGANIZATION OF THIS DOCUMENT

 The rest of this document consists of the following components:
    GLOSSARY
       The concepts introduced briefly in the section above are more
       formally defined, and their manner of representation in the
       protocol specified.
    MP FUNCTIONS
       The command sequence is defined by which a user process
       initiates each of the logical functions (e.g., Distribution,
       Recording, Delivery) which can be performed by a Mail server
       process.
    EXAMPLE
       An example of the command-response exchange between a user and
       server is given.
    COMMAND SUMMARY
       A summary of MP commands is given.
    COMMAND REPLIES
       Reply code assignments are given and briefly explained.

White [Page 4] RFC 524 A Proposed Mail Protocol 13 June 1973

    FORMAL SYNTAX
       The formal syntax of the command language is specified.
 In all sections but the last (i.e., the formal syntax presentation),
 verbose keyword forms are employed, in the interests of clarity.
 These verbose forms have no existence anywhere but in this document;
 in implementing a Mail user or server process, the terse keyword
 forms which appear in the formal syntax presentation are to be
 employed

GLOSSARY

 Terms are listed here in alphabetical order.  Words or phrases which
 appear in the definitions with initial letters capitalized are
 themselves formally defined elsewhere in the glossary.
 ACCESS LIST (for a piece of Recorded Mail)
    That set of individuals with access to a piece of Recorded Mail,
    and for each such individual, the type(s) of access granted to
    him.
    An Access List is represented in the Protocol as a series of
    command pairs (juxtaposed in the command stream), each pair
    consisting of an ACCESS command followed immediately (and
    optionally) by an ACCESSTYPES command.  Each pair of commands
    corresponds to one individual in the set.
       ACCESS <individual> <CA>
       ACCESSTYPE <accesstypes> <CA>
          Command arguments identify the Individual to whom access is
          granted, and specify the kind(s) of access allowed him.
          Either Read Access, Controlling Access, or both may be
          granted.
          If no Individual is specified, All is implied.  In the
          absence of an explicit ACCESSTYPES command, one with only
          Read Access specified is to be assumed.
       In the absence of an explicit Access List, one granting Read
       Access to All and Controlling Access to the Author(s) and the
       Clerk is to be assumed.

White [Page 5] RFC 524 A Proposed Mail Protocol 13 June 1973

 ACKNOWLEDGMENT (for a piece of Mail)
    A form of Unrecorded Mail, generated by a Distribution Agent,
    whose Recipient is the Monitor for a previous piece of Mail, which
    acknowledges Delivery -- successful or otherwise -- to the
    Recipient(s) of that first piece of Mail.
    An Acknowledgment bears the Serial Number of the Mail it
    acknowledges, as the Reference Serial Number.
 ACKNOWLEDGMENT CONDITION (for Acknowledgments)
    The attribute of an Acknowledgment which determines the
    circumstances under which it will be generated by the Distribution
    Agent.
    The following Acknowledgment Conditions are defined:
       ALWAYS
          Acknowledgment is given when all Deliveries are complete,
          regardless of whether or not they are all completed
          successfully.
       FAILURE
          Acknowledgment is given when all Deliveries are complete if
          and only if Delivery to one or more Recipient(s) fails.
       NEVER
          An Acknowledgment is never made.
    An Acknowledgment Condition is represented in the Protocol by the
    command:
 ACKCONDITION <ackcondition> <CA>
    In the absence of an explicit ACKCONDITION command, one with an
    argument of FAILURE is to be assumed.
 ACKNOWLEDGMENT TYPE (for Acknowledgments and Progress Reports)
    The attribute of an Acknowledgment or Progress Report which
    determines the nature of its Content.

White [Page 6] RFC 524 A Proposed Mail Protocol 13 June 1973

    The following Acknowledgment Types are defined:
       TERSE
          The Content of a TERSE Acknowledgment or Progress Report is
          specified by the Protocol to be an unembellished list of the
          Mail's Recipient(s), and the current Delivery Status for
          each (except that those Recipient(s) whose Delivery Status
          is SUCCESSFUL shall not be included in the list).
          The Content of a TERSE Acknowledgment is one or more
          instances of the following:
             <deliverystatus> <individual> <CRLF>
          TERSE Acknowledgments and Progress Reports are intended to
          be process-readable.
       VERBOSE
          The Content of a VERBOSE Acknowledgment or Progress Report
          is not specified by the Protocol, but might include a list
          of those Recipient(s) to whom the Mail could not be
          delivered and why, the times at which Delivery was made to
          others, etc.
          VERBOSE Acknowledgments and Progress Reports are intended to
          be human-readable.
    An Acknowledgment Type is represented in the Protocol by the
    command:
       ACKTYPE <acktype> <CA>
    In the absence of an explicit ACKTYPE command, one with an
    argument of TERSE is to be assumed.
 ALL
    Every conceivable Individual.
 AUTHOR (of a piece of Mail)
    An Individual (there may be more than one) given formal
    recognition for having authored a piece of Mail.

White [Page 7] RFC 524 A Proposed Mail Protocol 13 June 1973

 AUTHOR LIST (for a piece of Mail)
    That set of Individuals who are Author(s) of a piece of Mail.
    An Author List is represented in the Protocol as an Individual
    List of type AUTHOR.
 CATALOG (of Recorded Mail)
    A named data base containing the Citation for each member of a set
    of logically related pieces of Recorded Mail.
 CATALOG LIST (for a Piece of Recorded Mail)
    That set of Catalogs which each contain the Citation for a piece
    of Recorded Mail
    A Catalog List is represented in the Protocol as a series of
    instances (juxtaposed in the command stream) of the following
    command.  Each instance corresponds to one Catalog in the set.
       CATALOG <catalog> <CA>
 CITATION (for a piece of Recorded Mail)
    The Static and Dynamic Attributes of a piece of Recorded Mail.
 CITATION COMPONENT
    Any one of the Static or Dynamic Attributes which comprise a
    Citation.
 CITATION RETRIEVAL (for a piece of Recorded Mail)
    The act of retrieving selected Citation Component(s).
 CITATION TEMPLATE
    A specified subset of the Citation Component(s) for a piece of
    Recorded Mail.
    A Citation Template is represented in the Protocol by the command:

White [Page 8] RFC 524 A Proposed Mail Protocol 13 June 1973

       CITATIONTEMPLATE <citationtemp> <CA>
    The argument is a list of Citation Component(s).  In the absence
    of an explicit CITATIONTEMPLATE command (or if the argument is
    null), one specifying Content only is to be assumed.
 CLERK
    That Individual who prepares a piece of Mail for Recording,
    Distribution, or Delivery.  Conceptually, the Individual with
    proof-reading responsibility for the piece of Mail.
    A Clerk is represented in the Protocol as an Individual List of
    type CLERK and length 1.
 COMMENTS (for a piece of Mail)
    An informal, perhaps verbose description of the Content of a piece
    of Mail, or any other information the Author(s) wish to have made
    accessible to the Recipient(s) of the Mail.
    Comments are represented in the Protocol by the command:
       COMMENTS <comments> <CA2>
    In the absence of an explicit COMMENTS command, one with a null
    argument is to be assumed.
 CONTENT (of a piece of Mail)
    It's text.
    Content is represented in the protocol by either of the two
    commands below:
       FILE <CA>
          The FILE command implies that the Content of the Mail will
          be transmitted (immediately) as a file using the FTP data
          transfer commands (e.g., BYTE, SOCK, TYPE) currently in
          effect.  FILE is exactly equivalent in use to an FTP STOR
          command (in its use of data transfer commands, in its
          establishment of the data connection, etc.), except that no
          pathname is required, and the server, rather than depositing
          the transmitted file in his file system, disposes of it in a
          manner appropriate for Mail.

White [Page 9] RFC 524 A Proposed Mail Protocol 13 June 1973

       TEXT <string> <CA2>
          The TEXT command implies that the Content of the Mail
          follows on the TELNET connection as a series of lines, each
          delimited from the preceding one by CR LF, and terminated
          finally by a CA2.
 CONTROLLING ACCESS (to a piece of Recorded Mail)
    The right of an Individual to modify a Dynamic Attribute of a
    piece of Recorded Mail.
    Recording Agents permit an Individual to modify a Dynamic
    Attribute of a piece of Recorded Mail if and only if he can
    properly identify himself as someone having Controlling Access to
    that Mail.
 CREATION DATE (of a piece of Mail)
    The date and time at which the final draft of a piece of Mail is
    completed by the Clerk before he releases it to a Delivery,
    Distribution, or Recording Agent for further processing.  A single
    Creation Date is associated with each piece of Mail.  In general,
    this date is different from the Delivery or Recording Date, since
    Mail often must be queued (for another host to come up) within the
    Delivery, Distribution, or Recording Agent's host before Delivery
    of Recording can occur.
    A Creation Date is represented in the Protocol by the command:
       CREATIONDATE <datetime> <CA>
 CUTOFF INTERVAL (for Distribution of a piece of Mail)
    That period of time, measured from the Distribution Date, after
    which the Distribution Agent is to abandon Delivery attempts for
    those Recipient(s) to whom Delivery has not yet been effected.
    A Cutoff Interval is represented in the Protocol by the command:
       CUTOFF <interval> <CA>
    In the absence of an explicit CUTOFF command, one specifying an
    Interval of 7 days is to be assumed.

White [Page 10] RFC 524 A Proposed Mail Protocol 13 June 1973

 DELIVERY (of a piece of Mail)
    The act of transmitting a piece of Mail to the host of one of it's
    Recipient(s).
 DELIVERY AGENT
    A process which effects Delivery of a piece of Mail.  A
    Distribution Agent is by nature also a Delivery Agent.
 DELIVERY DATE (of a piece of Mail to one of its Recipient(s))
    The date and time at which a piece of Mail is Delivered by the
    Delivery Agent to a Recipient's system.  A multitude of Delivery
    Dates, one for each Recipient, are associated with each piece of
    Mail.
 DELIVERY STATUS (for a piece of Mail with respect to a Recipient)
    A measure of the extent to which a Delivery Agent has been
    successful, at a given point in time, in Delivering a piece of
    Mail to one of its Recipient(s).  A multitude of Delivery Status',
    one for each Recipient, are associated with each piece of Mail.
    The following Delivery Status' are defined:
       FAILED
          Delivery was rejected by the Recipient's system (e.g., the
          connection request was rejected, the Mail server process
          doesn't support Delivery, the Recipient was not recognized
          by the server).
       SUCCESSFUL
          Delivery was accomplished successfully.
       TIMED OUT
          Either the Recipient's host was disconnected from the Net at
          every Delivery attempt, or no Mail server process has ever
          responded to the connection attempt.  Hope of Delivery has
          been abandoned.

White [Page 11] RFC 524 A Proposed Mail Protocol 13 June 1973

       WAITING
          Either the Recipient's host has been disconnected from the
          Net at every Delivery attempt, or no Mail server process has
          yet responded to the connection attempt.  Delivery attempts
          are continuing periodically.
       UNATTEMPTED
          No delivery attempt has yet been made.
 DELIVERY TYPE (for a Delivery)
    The nature of the piece of Mail being delivered.
    The following Delivery Types are defined:
       FORWARD
          A Delivery of type FORWARD represents a piece of Recorded or
          Unrecorded Mail which is being Forwarded.
       MAIL
          A Delivery of type MAIL represents a piece of Recorded or
          Unrecorded Mail whose ultimate source is an Individual.
          This is the "normal" Delivery type.
       NEGATIVE ACKNOWLEDGMENT
          A Delivery of type NEGATIVE ACKNOWLEDGMENT represents a
          piece of Unrecorded Mail generated by a Distribution Agent
          and acknowledging unsuccessful or partially unsuccessful
          Delivery of a previous piece of Mail (identified by
          Reference Serial Number) to it's Recipient(s).  The
          Recipient for this piece of "system" Mail is the Monitor for
          the previous piece of Mail.
       POSITIVE ACKNOWLEDGMENT
          A Delivery of type POSITIVE ACKNOWLEDGMENT represents a
          piece of Unrecorded Mail generated by a Distribution Agent
          and acknowledging successful Delivery of a previous piece of
          Mail (identified by Reference Serial Number) to it's
          Recipient(s).  The Recipient for this piece of "system" Mail
          is the Monitor for the previous piece of Mail.

White [Page 12] RFC 524 A Proposed Mail Protocol 13 June 1973

       PROGRESS REPORT
          A Delivery of type PROGRESS REPORT represents a piece of
          Unrecorded Mail generated by a Distribution Agent and
          reporting the Delivery of a previous piece of Mail
          (identified by Reference Serial Number) to it's
          recipient(s).  The Recipient for this piece of "system" Mail
          is the Monitor for the previous piece of Mail.
       REPLY
          A Delivery of type REPLY represents a piece of Recorded or
          Unrecorded Mail generated in reply (or pertaining) to a
          previous piece of Mail (identified by Reference Serial
          Number).
    Delivery Type is represented in the Protocol by the command:
       DELIVERYTYPE <deliverytype> <CA>
    In the absence of an explicit DELIVERYTYPE command, one with
    argument of MAIL is to be assumed.
 DISTRIBUTE DATE (for a piece of Mail)
    The date and time at which a piece of Mail is presented to a
    Distribution Agent for Distribution.
 DISTRIBUTION (of a piece of Mail)
    The act of Delivering a piece of Mail to its Recipient(s).
    Distribution can be effected by either the Clerk's Delivery Agent,
    or by a Distribution Agent acting on his behalf.
 DISTRIBUTION AGENT
    A Mail server process which acts as intermediary in the delivery
    process by accepting Mail for Recipient(s) in hosts other than its
    own, and then assuming responsibility for Delivering the Mail to
    them and returning Acknowledgment to the appointed Monitor.
 DISTRIBUTION LIST
    In the Delivery or Distribution of a piece of Mail, that set of
    Individuals who are to receive Delivery of the Mail.

White [Page 13] RFC 524 A Proposed Mail Protocol 13 June 1973

    In the Recording of Mail, that set of Individuals who have
    received formal and authorized Delivery of a piece of Mail.  The
    list is kept current by Distribution Agents.  Of course, any
    Individual with Read Access to the Mail can himself Deliver it
    informally to anyone he chooses without that fact's being
    reflected in the Distribution list.
    A Distribution List is represented in the Protocol as a series of
    command quintuplets (juxtaposed in the command stream), each
    quintuplet consisting of a RECIPIENT command, followed immediately
    (and optionally) by any or all of the following in the order
    given: a GENERALDELIVERY, a GREETING, a SIGNATURE, and a
    DISPOSITION command.
    Each quintuplet corresponds to one individual in the set.
       RECIPIENT <individual> <CA>
       GENERALDELIVERY <CA>
          This command is appropriate only in the context of the
          Delivery function.  If the previous RECIPIENT command
          illicits the reply:
             474 Recipient unrecognized: is General Delivery
          OK?
          the issuance of the GENERALDELIVERY command constitutes
          consent to proceed with General Delivery to that Recipient.
          If no such consent is given, the RECIPIENT command stands
          rejected.  Unsolicited (i.e., unprompted for) GENERAL
          DELIVERY commands in the Distribution List are treated by
          the server as NOPs.
       GREETING <greeting> <CA>
          The GREETING command specifies the Greeting to be seen by
          the Recipient.
          If the first quintuplet in the list contains no GREETING
          command, one with a null argument is assumed.  Thereafter,
          in the absence of an explicit GREETING command, one
          identical to that for the previous quintuplet is assumed.
       SIGNATURE <signature> <CA>
          The SIGNATURE command specifies the Signature to be seen by
          the Recipient.

White [Page 14] RFC 524 A Proposed Mail Protocol 13 June 1973

          If the first quintuplet in the list contains no SIGNATURE
          command, one with a null argument is assumed.  Thereafter,
          in the absence of an explicit SIGNATURE command, one
          identical to that for the previous quintuplet is assumed.
       DISPOSITION <disposition> <CA>
          The DISPOSITION command identifies the intent with which the
          Mail is Delivered to the Recipient by the Author(s), and may
          take any, all, or none of the following as arguments:
             RSVP
                The Author(s) request a Reply from the Recipient.
             ACTION
                The Author(s) expect some action on the part of the
                Recipient.  If ACTION doesn't appear, then the Mail is
                intended for the Recipient's information only.
             INTERRUPT
                The Author(s) declare that examination of the Mail by
                the Recipient is urgent.  In such cases, the
                Recipient's Mail server process may, upon Delivery,
                choose to interrupt the Recipient if he happens to be
                logged in at a terminal.
          No specific action in response to the presence of any of
          these arguments is required; the server is free if he likes
          to treat DISPOSITION commands as NOPs.
          The absence of a DISPOSITION command implies one with no
          arguments (i.e., for the Recipient's information only, no
          Reply required, and not urgent).
 DYNAMIC ATTRIBUTES (of a piece of Recorded Mail)
    Those attributes of a piece of Recorded Mail -- Distribution List,
    Access List, and Catalog List -- which, though given initial
    values at Recording Time, can always be modified by an Individual
    with Controlling Access to the piece of Mail.
 FORWARDING (of Mail received for an Individual)
    The act of transferring that set of Mail which has been previously
    Delivered to but not Read by an Individual, to another Individual.

White [Page 15] RFC 524 A Proposed Mail Protocol 13 June 1973

    Users who are known at more than one host can cause their unRead
    Mailto be gathered in to a central location by performing the
    Forwarding function at each such host (both Individuals being, in
    this case, instances of the same User).  Mail which has been
    Forwarded is considered to have been Read at its source.
 FORWARDEE
    That Individual whose Delivered but UnRead Mail is to be
    Forwarded.
    A Forwardee is represented in the Protocol as an Individual List
    of type FORWARDEE and length 1.
 GENERAL DELIVERY (of a piece of Mail to an unrecognized Recipient)
    The act on the part of a server of accepting Delivery of a piece
    of Mail on behalf of an intended Recipient whose name the server
    doesn't recognize.  The server retains the Recipient's name, and
    makes it and the other information provided by the user process
    available to some competent person, who attempts to make sense of
    the Recipient's name.  If the Recipient is recognized, the Mail is
    'hand' delivered to the appropriate Individual.
    General Delivery of a piece of Mail to one of its intended
    Recipient(s) is performed only after the server informs the user
    process of its intent and receives the user process' consent.  If
    that consent is not given, or if the server doesn't implement
    General Delivery, the server rejects the Delivery attempt for that
    Recipient.
    Consent for General Delivery is represented in the Protocol by the
    command
       GENERALDELIVERY <CA>
 GREETING (for the Delivery of a piece of Mail to a Recipient)
    A short greeting to a Recipient of a piece of Mail. 'Dear Dave' is
    a valid and perhaps typical Greeting.
    A Greeting is represented in the Protocol by the command:
       GREETING <greeting> <CA>

White [Page 16] RFC 524 A Proposed Mail Protocol 13 June 1973

 ID (for an Individual)
    The password which an Individual may have to present to a Mail
    server process, to prove his identity.
    An Id is represented in the Protocol by the command:
       ID <id> <CA>
    Ids have nothing to do with accounting, and when required by a
    server, they're required only to protect that server from forgery
    or misrepresentation.
 INDIVIDUAL
    An instance of a User, identified by NIC Ident, or by the
    combination of host and Mailbox Name.
 INDIVIDUAL LIST (of type "t" and length "n")
    A set of Individuals.
    An Individual List is represented in the Protocol as a series of
    "n" command pairs (juxtaposed in the command stream), each pair
    consisting of a "t" command, followed immediately by an ID
    command.  Each pair corresponds to one Individual in the set.
    The ID command is given by the Mail user process at the option of
    the Mail server process; and whenever the server requires it, he
    must prompt for it with an appropriate reply to the preceding "t"
    command.  If no such prompt is given, the user process is not
    obliged to provide the ID command, but may if it chooses, in which
    case the server is obliged to treat it as if it had been prompted
    for and found correct.
    The ID command is a mechanism by which the server can assure
    himself that the user process is not acting without proper
    authorization from the Individual(s) involved, i.e., a mechanism
    by which a server can protect himself against forgery,
    misrepresentation, etc.
       "t" <individual> <CA>
       ID <id> <CA>

White [Page 17] RFC 524 A Proposed Mail Protocol 13 June 1973

 MAIL
    A body of text communicated from one set of Individual(s) to
    another, in less than (but ideally approaching) real time.
 MAILBOX NAME
    The name a User employs at a host to send and receive Mail.
 MONITOR (for a piece of Mail)
    The Individual who is the recipient for Acknowledgments and
    Progress Reports.
    A Monitor is represented in the Protocol as an Individual List of
    type MONITOR and length 1.
    Monitor defaults to the Clerk if not explicitly specified.
 PROGRESS REPORT (for a piece of Mail)
    A form of Unrecorded Mail, generated periodically during the
    distribution process by a Distribution Agent, whose Recipient is
    the Monitor for a previous piece of Mail, and whose Content is a
    list of the Recipient(s) and the current Delivery Status for each.
    A Progress Report bears the Serial Number of the Mail whose status
    it reports, as the Reference Serial Number.
 PROTOCOL
    The Mail Protocol (MP).
 READ (a piece of previously-Delivered Mail)
    The act, on the part of the User, of examining a piece of
    Delivered Mail.
 READ ACCESS (to a piece of Recorded Mail)
    The right of an Individual to retrieve the Content of a piece of
    Recorded Mail.
    Recording Agents permit an Individual to retrieve the Content of a
    piece of Recorded Mail if and only if he can properly identify
    himself as someone having Read Access to that Mail.  An Individual
    can retrieve the Citation (except Content) from the Recording
    Agent independently of whether or not he has Read Access to the
    Mail.

White [Page 18] RFC 524 A Proposed Mail Protocol 13 June 1973

 READ DATE (of a piece of Mail for one of its Recipient(s))
    The date and time, necessarily following Delivery, at which a
    piece of Mail is Read by a Recipient.  A multitude of Read Dates,
    one for each Recipient, are associated with each piece of Mail.
 RECIPIENT (of a piece of Mail)
    An Individual who has or is to receive Delivery of a piece of
    Mail.
 RECORDED MAIL
    A piece of Mail whose Citation is available on a long-term
    (indefinite) basis from a Recording Agent.
 RECORDING
    The service provided by a Recording Agent.
 RECORDING AGENT
    A Mail server process which accepts Mail, permanently Records its
    Citation, and assigns a pathname by which that information can at
    any time be retrieved by an Individual with appropriate access.
 RECORDING DATE
    The date and time at which a piece of Mail is presented to a
    Recording Agent for Recording.  A single Recording Date is
    associated with each piece of Recorded Mail.
 REFERENCE SERIAL NUMBER (for an Acknowledgment, Progress Report, or
    Reply)
    The Serial Number of the piece of Mail to which an Acknowledgment,
    Progress Report, or Reply refers.
    A Reference Serial Number is represented in the protocol by the
    command:
       REFERENCESERIAL <serialnumber> <CA>
    In the absence of an explicit REFERENCESERIAL command, no Serial
    Number is to be assumed.

White [Page 19] RFC 524 A Proposed Mail Protocol 13 June 1973

 REPLY (to a previous piece of Mail)
    A piece of Recorded or Unrecorded Mail whose Author(s) are
    Recipient(s) of a previous piece of Mail, and which replies or
    pertains to that same piece of Mail and bears its Serial Number,
    as the Reference Serial Number.
 REPORT INTERVAL (for a Progress Report)
    The interval between Progress Reports.
    A Report Interval is represented in the Protocol by the command:
       REPORTINTERVAL <interval> <CA>
    In the absence of an explicit REPORTINTERVAL command, one with an
    argument whose value is effectively infinite is to be assumed
    (i.e., no Progress Reports are to be made).
 REQUESTOR
    The Individual on whose behalf a Mail user process connects to and
    interacts with a Mail server process.
    A Requestor is represented in the Protocol as an Individual List
    of type REQUESTOR and length 1.
 SERIAL NUMBER (for a piece of Mail)
    A short-term identifier, assigned to a piece of Mail by the Clerk
    (or his system), which accompanies Acknowledgments, Progress
    Reports, and Replies, and is used to correlate the latter with the
    former.  The lifetime of a Serial Number is conceptually from its
    assignment by the Clerk until the Delivery of the Recipient(s)
    Reply(s) to the Author(s) (or until their decision to send no
    reply).
    A serial Number is represented in the Protocol by the command:
       SERIAL <serialnumber> <CA>
    In the absence of an explicit SERIAL command, no Serial Number is
    to be assumed.
 SIGNATURE (for the delivery of a piece of Mail to a Recipient)
    A human-readable indication of the Author(s) of a piece of Mail.
    The string 'Jim and Dick' is a valid Signature.

White [Page 20] RFC 524 A Proposed Mail Protocol 13 June 1973

    A Signature is represented in the Protocol by the command:
       SIGNATURE <signature> <CA>
 STATIC ATTRIBUTES (of a piece of Recorded Mail)
    Those attributes of a piece of Recorded Mail -- Content, Title,
    Comments, Author(s), Clerk, and Creation Date -- which are forever
    fixed at Recording Time, and hence can never be modified.
    Static Attributes can be independently specified with commands
    described elsewhere, or specified collectively by reference to an
    existing piece of Recorded Mail.  The command which follows
    assigns to the current piece of Mail the Static Attributes of the
    piece of Recorded Mail it references, and is exactly equivalent to
    an appropriate set of TITLE, COMMENTS, etc.  commands.
       LOCATION <fileaddr> <CA>
 TITLE (of a piece of Mail)
    A concise description of the Content of a piece of Mail.
    A Title is represented in the Protocol by the command:
       TITLE <title> <CA>
    In the absence of an explicit TITLE command, one with a null
    argument is to be assumed.
 UNRECORDED MAIL
    Mail which is never presented to a Recording Agent for permanent
    storage and cataloging, but which is simply Delivered to its
    Recipient(s) by a Delivery Agent.
 UPDATE REQUEST (to a Recording Agent for a piece of Recorded Mail)
    A request made of a Recording Agent to add, replace, or delete an
    Individual from the Access or Distribution List for a piece of
    Mail; or to add or delete a Catalog from the Catalog List.
    An Update Request is represented in the Protocol by the command:
       UPDATETYPE <updatetype> <CA>
    followed immediately in the command stream by an Access,
    Distribution or Catalog List.

White [Page 21] RFC 524 A Proposed Mail Protocol 13 June 1973

 USER
    A process or human who sends and/or receives Mail.
 USER VERIFICATION
    The act of verifying an ID as that of a specified Individual.
 USER VERIFICATION AGENT
    A Mail server process which performs User Verification

MP FUNCTIONS

 A MP function is the request by a Mail user process and the
 subsequent performance by a server, of a major task related to the
 management of Mail.  The following functions are defined:
    RECORDING
    DELIVERY
    DISTRIBUTION
    FORWARDING
    CITATION RETRIEVAL
    UPDATE CITATION
    USER VERIFICATION
 One might expect that within the Network there would be just a few
 Recording Agents (who implement the Recording, Citation Retrieval,
 and Update Citation functions); a few Distribution Agents (who
 implement the Distribution function); one or two User Verification
 Agents (who implement the User Verification Function); and many hosts
 who implement the Delivery and Forwarding functions.
 In general, a host is free to implement any, all, or none of the
 functions defined by the Protocol; and a host is free to require a
 login (for purposes of accounting) before permitting a user process
 access to any of the function(s) it has implemented.
 An FTP server process who chooses to not implement MP or a particular
 MP function simply rejects the command that requests the
 unimplemented server with the reply:
    400 Function not implemented.
 A server who chooses to require login before allowing access to the
 MP subsystem or to an MP function, simply rejects the command that
 requests the charged-for service with the reply:

White [Page 22] RFC 524 A Proposed Mail Protocol 13 June 1973

    332 Login first, please.
 The functions defined in MP are:
    RECORDING
       The Recording function is invoked with the command:
          RECORD <CA>
       Once this command is given, the user process shall provide the
       following (in any order that suits it):
          (1)   Any Static Attributes desired.
             Content and Clerk are required.  Defaults for other
             Static Attributes (applied by the server if the
             appropriate commands don't appear) are as follows:
                Title or Comments as specified in the glossary.
                Author to the Clerk.
                Creation Date to the Recording Date.
          (2)   Initial values for any Dynamic Attributes desired.
             Defaults (applied by the server if the appropriate
             commands don't appear) are as follows:
                Distribution and Catalog Lists to null.
                Access List as specified in the glossary.
       The Recording function is terminated with either of the
       commands:
          EXIT <CA>    or    ABORT <CA>
       EXIT represents normal termination, and causes the server to
       perform the Recording function for which parameters have just
       been given.  ABORT represents abnormal termination and effects
       exit from the function with no action having been taken by the
       server; the whole command exchange, beginning with RECORD, is
       therefore a NOP.

White [Page 23] RFC 524 A Proposed Mail Protocol 13 June 1973

    DELIVERY
       The Delivery function is invoked with the command:
          DELIVER <CA>
       Once this command is given, the user process shall provide the
       following (in any order that suits it):
          (1)   Any Static Attributes desired.
             Content is required.  Defaults for other Static
             Attributes (applied by the server if the appropriate
             commands don't appear) are as follows:
                Title or Comments as specified in the glossary.
                Clerk to null
                Author to the Clerk.
                Creation Date to the Delivery Date.
          (2)    Any Dynamic Attributes desired.
             Distribution List is required.  Defaults (applied by the
             server if the appropriate commands don't appear) are as
             follows:
                Catalog List to null
                Access List as specified in the glossary.
                   Both of these attributes are for the Recipient's
                   information only when presented in the context of
                   Delivery, so defaulting them to null simply implies
                   that the Clerk doesn't desire that they be
                   communicated to the Recipient.
          (3)   Any or all of the following optional parameters:
             (a) Delivery Type

White [Page 24] RFC 524 A Proposed Mail Protocol 13 June 1973

             (b) Acknowledgment Type
                The specification of this parameter is appropriate if
                and only if the Delivery Type is POSITIVE or NEGATIVE
                ACKNOWLEDGMENT or PROGRESS REPORT.  In this context,
                Acknowledgment Type tells the server how to interpret
                the Content of the Acknowledgment.
             (c) Serial Number
                The Serial Number assigned to the piece of Mail being
                Delivered.  This parameter is inappropriate unless the
                Delivery type is FORWARD (in which case the Serial
                Number is the one preserved from the previous
                Delivery), MAIL, or REPLY.
             (d) Reference Serial Number
                The Serial Number assigned to the piece of Mail to
                which the current piece of Mail is either an
                Acknowledgment, Progress Report, or Reply.  The
                specification of this parameter is therefore
                inappropriate if the Delivery Type is MAIL.
       The Delivery function is terminated with either of the
       commands:
          EXIT <CA>    or    ABORT <CA>
       EXIT represents normal termination, and causes the server to
       perform the Delivery function for which parameters have just
       been given.  ABORT represents abnormal termination and effects
       exit from the function with no action having been taken by the
       server; the whole command exchange, beginning with DELIVER, is
       therefore a NOP.
    DISTRIBUTION
       The Distribution function is invoked with the command:
          DISTRIBUTE <CA>
       Once this command is given, the user process shall provide the
       following (in any order that suits it):
          (1) Any Static Attributes desired.

White [Page 25] RFC 524 A Proposed Mail Protocol 13 June 1973

             Content is required.  Defaults for other Static
             Attributes (applied by the server if the appropriate
             commands don't appear) are as follows:
                Title or Comments as specified in the glossary.
                Clerk to null
                Author to the Clerk.
                Creation Date to the Delivery Date.
          (2) Any Dynamic Attributes desired.
             Distribution List is required.  Defaults (applied by the
             server if the appropriate commands don't appear) are as
             follows:
                Catalog List to null
                Access List as specified in the glossary.
                   Both of these attributes are for the Recipient(s)
                   information only when presented in the context of
                   Distribution, so defaulting them to null simply
                   implies that the Clerk doesn't desire that they be
                   communicated to the Recipient(s).
          (3) Any or all of the following optional parameters:
                (a) Delivery Type
                   MAIL, FORWARD, or REPLY only.
                (b) Serial Number
                   The Serial Number of the Mail being Distributed.
                   The Distribution Agent will relay this Serial
                   Number to each Recipient at Delivery.
                (c) Reference Serial Number
                   The Serial Number of the piece of Mail to which the
                   current piece of Mail is a Reply.  The Distribution
                   Agent will relay this Serial Number to each
                   Recipient at Delivery.  The specification of this
                   parameter is appropriate if and only if the
                   Delivery Type is REPLY.

White [Page 26] RFC 524 A Proposed Mail Protocol 13 June 1973

                (d) Acknowledgment Condition
                   An Acknowledgment is requested from the
                   Distribution Agent if and only if the
                   Acknowledgment Condition is other than NEVER.
                (e) Acknowledgment Type
                (f) Cutoff Interval
                (g) Report Interval
                   Progress Reports are requested from the
                   Distribution Agent if and only if this parameter is
                   specified explicitly.
                (h) Monitor
                   This parameter is ignored unless either an
                   Acknowledgment or Progress Reports (or both) are
                   requested.
          The Distribution function is terminated with either of the
          commands:
             EXIT <CA>    or    ABORT <CA>
          EXIT represents normal termination, and causes the server to
          perform the Distribution function for which parameters have
          just been given.  ABORT represents abnormal termination and
          effects exit from the function with no action having been
          taken by the server; the whole command exchange, beginning
          with DISTRIBUTE, is therefore a NOP.
    FORWARDING
       The Forwarding function is invoked with the command:
          FORWARD <CA>
       Once this command is given, the user process shall provide the
       following (in any order that suits it):
          (1) Forwardee

White [Page 27] RFC 524 A Proposed Mail Protocol 13 June 1973

          (2) Distribution list
             This is the set of Individual(s) to whom the Mail is to
             be Forwarded.
       The Forwarding function is terminated with either of the
       commands:
          EXIT <CA>    or    ABORT <CA>
       EXIT represents normal termination, and causes the server to
       perform the Forwarding function for which parameters have just
       been given.  ABORT represents abnormal termination and effects
       exit from the function with no action having been taken by the
       server; the whole command exchange, beginning with FORWARD, is
       therefore a NOP.
    CITATION RETRIEVAL
       The Citation Retrieval function is invoked with the command:
          RETRIEVE <CA>
       Once this command is given, the user process shall provide the
       following (in any order that suits it):
          (1) The pathname of the piece of Mail whose Citation is to
             be retrieved:
             PATHNAME <pathname> <CA>
          (2) Any or all of the following optional parameters:
             (a) Citation Template
             (b) Requestor
                This parameter is required if and only if Content is
                requested and Read Access happens not to be granted to
                All, in which case the server verifies that the
                Requestor has Read Access to the piece of Mail.
             (c) FILE <CA>
                This command is appropriate if and only if Content is
                requested.  The presence of this command implies that
                the Content of the Mail is to be returned to the user
                process (following the return on the TELNET connection

White [Page 28] RFC 524 A Proposed Mail Protocol 13 June 1973

                of any other Citation Component(s) requested) as a
                file using the FTP data transfer commands (e.g., BYTE,
                SOCK, TYPE) currently in effect.  FILE is exactly
                equivalent in effect to an FTP RETR command (in its
                use of data transfer commands, in its establishment of
                the data connection etc.) except that no pathname is
                required.
                In the absence of a FILE command, Content is returned
                on the TELNET connection like any other Citation
                Component.
                The server returns the Citation Components in the
                order requested by the user process (except that
                Content, if requested as a file, is always returned
                after the 'end of citation' indication), each as a
                reply whose numeric code is 172 and whose text is
                exactly the command normally used to communicate that
                same parameter to the server.  A reply whose numeric
                code is 173 terminates the reply list.
                Title and Content, which (in general) may each contain
                the TELNET New Line sequence (CR LF), are represented
                as continued replies, using the FTP reply continuation
                convention (see the FTP protocol document).  The first
                four characters of each reply line except the first
                and last are blanks inserted by the server which must
                be deleted by the user process to correctly recover
                the value of the Title or Content.
       The Citation Retrieval function is terminated with either of
       the commands:
          EXIT <CA>    or    ABORT <CA>
       EXIT represents normal termination, and causes the server to
       perform the Citation Retrieval function for which parameters
       have just been given.  ABORT represents abnormal termination
       and effects exit from the function with no action having been
       taken by the server; the whole command exchange, beginning with
       RETRIEVE, is therefore a NOP.

White [Page 29] RFC 524 A Proposed Mail Protocol 13 June 1973

    UPDATE CITATION
       The Update Citation function is invoked with the command:
          UPDATE <CA>
       Once this command is given, the user process shall provide the
       following (in any order that suits it):
          (1) Requestor
             This parameter is required unless Controlling Access has
             been granted to All, in which case it is treated as a NOP
             if given.  The server verifies that the Requestor has
             Controlling Access to the piece of Mail.
          (2) One or more Update Requests
       The Update Citation function is terminated with either of the
       commands:
          EXIT <CA>    or    ABORT <CA>
       EXIT represents normal termination, and causes the server to
       perform the Update Citation function for which parameters have
       just been given.  ABORT represents abnormal termination and
       effects exit from the function with no action having been taken
       by the server; the whole command exchange, beginning with
       UPDATE, is therefore a NOP.
    USER VERIFICATION
          The User Verification function is invoked with the command:
             VERIFY <CA>
          Once this command is given, the user process shall specify
          any number of Requestors.
          The server prompts for the Id for each, the user process
          provides it, and the server returns a reply whose numeric
          code is 272 is the Id is correct or 472 otherwise.
       The User Verification function is terminated with either of the
       commands:
          EXIT <CA>    or    ABORT <CA>

White [Page 30] RFC 524 A Proposed Mail Protocol 13 June 1973

EXAMPLE

 In the example below, a short message is recorded for public access,
 and distributed to a single recipient.  The user process is assumed
 already connected to the server.
    Note: This would be the implementation of NIC Journal Submission,
    where the NIC is understood to be both a Recording and
    Distribution Agent.
 Replies from the server are in brackets.
    MAIL <CA>
       The Mail system is invoked.
       [261 RE DE DI FW CI UP UV -- supported.]
    REC <CA>
       The Recording function is invoked.
       [200 OK.]
    TITL SMFS Runs on TENEX 1.31 at the NIC <CA>
       A Title is given
       [200 OK.]
    TEXT The NIC came up on TENEX 1.31 on 1-APR. <CRLF> I tried SMFS
    here on the new monitor and it <CRLF> works fine.  I don't
    understand why I had <CRLF> problems running your copy of the code
    at <CRLF> BBN-TENEX.  Are you still unable to reference <CRLF> the
    same archived file from two different <CRLF> TENEXs? <CA2>
       The Content of the message is entered.
       [200 OK.]
    CLER WHITE@SRI-ARC <CR>
       The Clerk is identified as White at SRI-ARC.
       [330 OK.  Now Id, please]
    ID id <CA>
       His Id is supplied.
       [200 OK.]

White [Page 31] RFC 524 A Proposed Mail Protocol 13 June 1973

    EXIT <CA>
       Exit from the Recording function is effected, and the pathname
       '15490' is returned by the Recording Agent for the now Recorded
       Mail.
       [270 15490 -- is assigned as the pathname.]
    DIST <CA>
       The Distribution function is invoked.
       [200 OK.]
    LOC SRI-ARC 15490 <CA>
       The message just recorded is specified for Distribution.
       [200 OK.]
    RECI * DHC <CA>
       The Recipient is specified via NIC Ident to be Dave Crocker at
       UCLA-NMC.
       [200 OK.]
    GREE Dave <CA>
       A Greeting is given.
       [200 OK.]
    DISP R
       A reply is requested.
       [200 OK.]
    SIGN Jim
       The message is signed.
       [200 OK.]
    ACKC A <CA>
       Acknowledgment of the Mail's Delivery is requested whether
       Delivery succeeds or fails..
       [200 OK.]
    ACKT T <CA>
       The Acknowledgment is to be terse.
       [200 OK.]

White [Page 32] RFC 524 A Proposed Mail Protocol 13 June 1973

    CUT 1 D <CA>
       If Delivery hasn't been effected within 24 hours, the attempt
       is to be abandoned (and an Acknowledgment of failure returned).
       The Monitor (to whom the Acknowledgment is sent) is allowed to
       default to the Clerk.
       [200 OK.]
    SERI serial <CA>
       A Serial Number is assigned for purposes of coordinating
       Acknowledgment and Reply.  A desirable implementation of the
       sender's user and server processes is one in which the Serial
       Number is assigned by the user process, rather than by the
       human user himself in such a way that his server process can
       automatically make the association between original Mail, and
       subsequent Acknowledgment and Reply.
       [200 OK.]
    EXIT <CA>
       Exit from the Distribution function is effected.
       [200 OK.]
    EXIT <CA>
       Exit from the Mail subsystem is effected.
       [200 OK.]

White [Page 33] RFC 524 A Proposed Mail Protocol 13 June 1973

COMMAND SUMMARY

 Every command requires at least one reply from the server.
 THOSE SPECIFIC TO MP
    ABORT <CA>
    ACCESS <individual> <CA>
    ACCESSTYPES <accesstypes> <CA>
    ACKCONDITION <ackcondition> <CA>
    ACKTYPE <acktype> <CA>
    AUTHOR <individual> <CA>
    CATALOG <catalog> <CA>
    CITATIONTEMPLATE <citationtemp> <CA>
    CLERK <individual> <CA>
    COMMENTS <comments> <CA>
    CREATIONDATE <datetime> <CA>
    CUTOFF <interval> <CA>
    DELIVER <CA>
    DELIVERYTYPE <deliverytype> <CA>
    DISPOSITION <disposition> <CA>
    DISTRIBUTE <CA>
    EXIT <CA>
    FILE <CA>
    FORWARD <CA>
    FORWARDEE <individual> <CA>
    GENERALDELIVERY <CA>
    GREETING <greeting> <CA>
    ID <id> <CA>
    LOCATION <fileaddr> <CA>
    MAIL <CA>
    MONITOR <individual> <CA>
    PATHNAME <pathname> <CA>
    RECIPIENT <individual> <CA>
    RECORD <CA>
    REFERENCESERIAL <serialnumber> <CA>
    REPORTINTERVAL <interval> <CA>
    REQUESTOR <individual> <CA>
    RETRIEVE <CA>
    SERIAL <serialnumber> <CA>
    SIGNATURE <signature> <CA>
    TEXT <string> <CA2>
    TITLE <title> <CA>
    UPDATE <CA>
    UPDATETYPE <updatetype> <CA>
    VERIFY <CA>

White [Page 34] RFC 524 A Proposed Mail Protocol 13 June 1973

 THOSE BORROWED FROM FTP
    The following commands borrowed from FTP are defined (also) as MP
    commands to support the transfer of the Content of a piece of Mail
    in 'file' form.  The reader is referred to the FTP protocol
    document for a description of their use and syntax.  The borrowed
    commands are:
       BYTE, SOCK, PASV, TYPE, STRU, MODE, REST, and SITE.
    The following commands borrowed from FTP are defined (also) as MP
    commands to permit changes of accounting parameters within the MP
    subsystem.  The accounting parameters in force when the subsystem
    is entered apply (if necessary) within the subsystem until
    changed.  Values to which the parameters may have been changed
    while in the subsystem continue in effect upon return to the FTP
    command space.  The borrowed commands are:
       USER, PASS, and ACCT.
    The following miscellaneous commands borrowed from FTP are defined
    also as MP commands:
       HELP and NOOP.

COMMAND REPLIES

 This list is undoubtedly incomplete; some crucial reply code
 assignments may be missing despite the author's attempt to foresee
 the kinds of interaction that might arise between user and server and
 the responses from the server that they would require.
    172 <A Citation Component>
        In response to the EXIT command which terminates the Citation
        Retrieval function.
    173 End of citation.
        Following a list of 172 replies.
    200 OK.
        This is the standard, positive acknowledgment used throughout
        the Protocol.

White [Page 35] RFC 524 A Proposed Mail Protocol 13 June 1973

    270 <pathname> -- is assigned as the pathname.
        In response to the EXIT command which terminates the Record
        function.
    271 <functionlist> -- supported.
        In response to the MAIL command by which the user process
        gains entry to the Mail subsystem.  This response is
        mandatory, and from it the user process can quickly determine
        what function(s) are supported by the server.
    272 Requestor is who he says he is.
        In response to an ID command in the User Verification
        function.  This reply informs the user process that the Id
        given is in fact that of the Individual specified.
    330 OK.  Now Id, please.
        In response to the first command in each pair of commands in
        an Individual List.  This reply requires the next command from
        the user process to be ID.
    332 Login first, please.
        In response to any command which  invokes a Mail function
        (e.g., RECORD, DISTRIBUTE, DELIVER), or to the MAIL command
        itself.  This reply implies that the requested function is
        supported by the server, but that the user is required to
        login before invoking it.
    400 Function not implemented.
        In response to any command which invokes a Mail function
        (e.g., RECORD, DISTRIBUTE, DELIVER), or to the MAIL command
        itself.  This reply implies that the requested function is not
        supported by the server.
    431 Incorrect Id.
        In response to the ID command in an Individual List command
        pair.  This reply implies that the Id specified was incorrect.

White [Page 36] RFC 524 A Proposed Mail Protocol 13 June 1973

    440 <Error relayed from Recording Agent>
        In response to the LOCATION command.  This reply implies that
        the server attempted to retrieve the specified piece of Mail
        from an FTP server but failed because it returned the error
        reply whose text is duplicated in the current reply.
    470 No such pathname.
        In response to the PATHNAME command (in the Citation Retrieval
        function).  This reply implies that the specified pathname is
        not recognized by the server.
    471 No unRead Mail to Forward.
        In response to the EXIT command which terminates the
        Forwarding Function.
    472 Requestor is NOT who he says he is.
        In response to an ID command in the User Verification
        function.  This reply informs the user process that the Id
        given is NOT that of the Individual specified.
    473 You don't have Read Access to the Mail.
        In response to the LOCATION command, or to the PATHNAME
        command in a Citation Retrieval function.  This reply implies
        that the Requestor doesn't have Read Access to the piece of
        Mail.
    474 Recipient unrecognized; is General Delivery OK?
        In response to an instance of the RECIPIENT command in a
        Distribution List (in the context of the Delivery function).
        This response implies that the Recipient in unrecognized, but
        that the server will attempt General Delivery to him if the
        user process responds with a GENERALDELIVERY command;
        otherwise the Recipient is rejected.
    475 That Individual is not at this host.
    570 No such NIC Ident or Mailbox Name.
        In response to any command in which a NIC Ident or Mailbox
        Name appears as an argument.  This reply implies that the
        Individual specified does not exist.

White [Page 37] RFC 524 A Proposed Mail Protocol 13 June 1973

    571 Invalid host.
        In response to any command in which a host address or standard
        host name appears as an argument.  This reply implies that no
        such host exists.
    572 No such catalog.
        In response to the CATALOG command.  This reply implies that
        no such Catalog exists.
    Any '500' reply.
 Any of the error replies associated with FTP RETR/STOR commands.

FORMAL SYNTAX

 The terse keyword forms to be employed in actually implementing a
 Mail user or server process are generated by deleting character(s)
 from the corresponding verbose forms.  Those deleted characters are
 included but enclosed in brackets throughout the description which
 follows.  Spaces can be used freely between terminal elements of the
 syntax, and in some cases, at least one space must separate two
 elements whose boundary could not otherwise be distinguished.
 <CA2>            ::= TELNET Go Ahead character
 <CA>             ::= TELNET new line (CR LF)
 <CRLF>           ::= CR LF
 <accesstypes>    ::= <readaccess> <controlaccess>
 <ackcondition>   ::= A[LWAYS] | F[AILURE] | N[EVER]
 <acktype>        ::= T[ERSE] | V[ERBOSE]
 <action>         ::= A[CTION] | null
 <catalog>        ::= <string>
 <citationcomp>   ::= D[ISTRIBUTION]L[IST] | A[CESS]L[IST] |
                      C[ATALOG]L[IST] | C[ON]T[ENT] |  T[ITLE] |
                      C[OM]M[ENTS] | AU[THOR] | CL[ERK] |
                      C[REATION]D[ATE]
 <citationtemp>   ::= <citationcomp> | <citationcomp>
                      <citationtemp>
 <command>        ::= <shortbody> <CA> | <longbody> <CA2>
 <comments>       ::= <string>
 <controlaccess>  ::= C[ONTROLLING] | null
 <count>          ::= decimal integer
 <date>           ::= <dayofmonth> / <month> / <year>
 <datetime>       ::= <date> <time>
 <dayofmonth>     ::= decimal integer, 1-31
 <days>           ::= <count> D[AYS]
 <deliverystatus> ::= F[AILED] | S[UCCESSFUL] | T[IMED OUT] |

White [Page 38] RFC 524 A Proposed Mail Protocol 13 June 1973

                      W[AITING] | U[NATTEMPTED]
 <deliverytype>   ::= F[ORWARD] | M[AIL] | N[EGATIVE
                      ACKNOWLEDGMENT] | P[OSITIVE
                      ACKNOWLEDGMENT] | P[ROGRESS]R[EPORT]
                      | R[EPLY]
 <disposition>    ::= <rsvp> <action> <interrupt>
 <fileaddr>       ::= <host> <pathname>
 <functionlist>   ::= <functiontype> | <functiontype>
                      <functionlist>
 <functiontype>   ::= RE[CORDING] | DE[LIVERY] | DI[STRIBUTION] |
                      F[OR]W[ARDING] | CI[TATION RETEiEVAL] |
                      UP[DATE] | U[SER]V[ERIFICATION]
 <globalname>     ::= * <nicident>
 <greeting>       ::= <string>
 <host>           ::= <hostname> | <hostaddress>
 <hostaddress>    ::= decimal integer, 0-255
 <hostname>       ::= standard host name
 <hour>           ::= decimal integer, 0-23
 <hours>          ::= <count> H[OURS]
 <individual>     ::= <localname> | <globalname>
 <interrupt>      ::= I[NTERRUPT] | null
 <interval>       ::= <days> | <hours> | <days> <hours>
 <localname>      ::= <mailbox> @ <host> | <mailbox> @
    NOTE: Host defaults to that of the server
 <longbody>       ::= COM[MENTS] <comments> |
                      TEXT <string>
 <mailbox>        ::= <string>
 <minute>         ::= decimal integer, 0-59
 <month>          ::= decimal integer, 1-12
 <nicident>       ::= <string>
 <id>             ::= <string>
 <pathname>       ::= <string>
 <readaccess>     ::= R[EAD] | null
 <rsvp>           ::= R[SVP] | null
 <serialnumber>   ::= <string>
 <shortbody>      ::= ABOR[T] |
                      ACC[ESS] <individual> |
                      ACKC[ONDITION] <ackcondition> |
                      ACKT[YPE] <acktype> |
                      AC[CESS]TY[PES] <accesstypes> |
                      AUTH[OR] <individual> |
                      CAT[ALOG] <catalog> |
                      CLER[K] <individual> |
                      CR[EATION]DA[TE] <datetime> |
                      CUT[OFF] <interval> |
                      C[ITATION]TEM[PLATE] <citationtemp> |
                      DELI[VER] |
                      DE[LIVERY]TY[PE] <delivverytype> |

White [Page 39] RFC 524 A Proposed Mail Protocol 13 June 1973

                      DISP[OSITION] <disposition> |
                      DIST[RIBUTE] |
                      EXIT |
                      FILE |
                      FOR[WARDE]E <individual> |
                      FOR[WARD] |
                      GEN[ERAL]D[ELIVERY] |
                      GREE[TING] <greeting> |
                      ID <ID> |
                      LOC[ATION] <fileaddr> |
                      MAIL |
                      MON[ITOR] <individual> |
                      PATH[NAME] <pathname> |
                      RECI[PIENT] <individual> |
                      REC[ORD] |
                      REQ[UESTO]R <individual> |
                      R[EFERENCE]SER[IAL] <serialnumber> |
                      R[EPORT]INT[ERVAL] <interval> |
                      SERI[AL] <serialnumber> |
                      SIGN[ATURE] <signature> |
                      TITL[E] <title> |
                      UPDA[TE] |
                      UP[DATE]TY[PE] <updatetype> |
                      VER[IFY]
 <signature>      ::= <string>
 <string>         ::= any non-zero number of visible characters
                      (in particular, CA and CA2 are excluded)
 <time>           ::= <hour> : <minute> <timezone>
 <timezone>       ::= EST | EDT | CST | CDT | MST | MDT | PST |
                      PDT | GMT
 <title>          ::= <string>
 <updatetype>     ::= A[DD] | R[EPLACE] | D[ELETE]
 <year>           ::= full year in decimal (e.g., 1973)
       [ This RFC was put into machine readable form for entry ]
             [ into the online RFC archives by Root 2/98 ]

White [Page 40]

/data/webs/external/dokuwiki/data/pages/rfc/rfc524.txt · Last modified: 2001/11/08 19:34 by 127.0.0.1

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