RFC 524: Proposed Mail Protocol

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>.




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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.





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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.





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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.




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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.






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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.






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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.






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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:









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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.





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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.







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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.








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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.





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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.






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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.



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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.



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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>







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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>







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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.



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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.






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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.



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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.



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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:




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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.






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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









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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.





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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.



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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







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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



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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.










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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>




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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.]






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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.]



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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.]























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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>





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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.






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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.








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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.




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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] |



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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> |



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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 ]












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RFC 524: Proposed Mail Protocol