rfc1725.txt

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RFC 1725                          POP3                     November 1994


         Discussion:
             The POP3 server issues a positive response with a line
             containing information for the maildrop.  This line is
             called a "drop listing" for that maildrop.

             In order to simplify parsing, all POP3 servers required to
             use a certain format for drop listings.  The positive
             response consists of "+OK" followed by a single space, the
             number of messages in the maildrop, a single space, and the
             size of the maildrop in octets.  This memo makes no
             requirement on what follows the maildrop size.  Minimal
             implementations should just end that line of the response
             with a CRLF pair.  More advanced implementations may
             include other information.

                NOTE: This memo STRONGLY discourages implementations
                from supplying additional information in the drop
                listing.  Other, optional, facilities are discussed
                later on which permit the client to parse the messages
                in the maildrop.

             Note that messages marked as deleted are not counted in
             either total.

         Possible Responses:
             +OK nn mm

         Examples:
             C: STAT
             S: +OK 2 320

      LIST [msg]

         Arguments:
             a message-number (optional), which, if present, may NOT
             refer to a message marked as deleted

         Restrictions:
             may only be given in the TRANSACTION state

         Discussion:
             If an argument was given and the POP3 server issues a
             positive response with a line containing information for
             that message.  This line is called a "scan listing" for
             that message.

             If no argument was given and the POP3 server issues a
             positive response, then the response given is multi-line.



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RFC 1725                          POP3                     November 1994


             After the initial +OK, for each message in the maildrop,
             the POP3 server responds with a line containing information
             for that message.  This line is also called a "scan
             listing" for that message.

             In order to simplify parsing, all POP3 servers are required
             to use a certain format for scan listings.  A scan listing
             consists of the message-number of the message, followed by
             a single space and the exact size of the message in octets.
             This memo makes no requirement on what follows the message
             size in the scan listing.  Minimal implementations should
             just end that line of the response with a CRLF pair.  More
             advanced implementations may include other information, as
             parsed from the message.

                NOTE: This memo STRONGLY discourages implementations
                from supplying additional information in the scan
                listing.  Other, optional, facilities are discussed
                later on which permit the client to parse the messages
                in the maildrop.

             Note that messages marked as deleted are not listed.

         Possible Responses:
             +OK scan listing follows
             -ERR no such message

         Examples:
             C: LIST
             S: +OK 2 messages (320 octets)
             S: 1 120
             S: 2 200
             S: .
               ...
             C: LIST 2
             S: +OK 2 200
               ...
             C: LIST 3
             S: -ERR no such message, only 2 messages in maildrop

      RETR msg

         Arguments:
             a message-number (required) which may not refer to a
             message marked as deleted

         Restrictions:
             may only be given in the TRANSACTION state



Myers & Rose                                                    [Page 8]

RFC 1725                          POP3                     November 1994


         Discussion:
             If the POP3 server issues a positive response, then the
             response given is multi-line.  After the initial +OK, the
             POP3 server sends the message corresponding to the given
             message-number, being careful to byte-stuff the termination
             character (as with all multi-line responses).

         Possible Responses:
             +OK message follows
             -ERR no such message

         Examples:
             C: RETR 1
             S: +OK 120 octets
             S: <the POP3 server sends the entire message here>
             S: .

      DELE msg

         Arguments:
             a message-number (required) which may not refer to a
             message marked as deleted

         Restrictions:
             may only be given in the TRANSACTION state

         Discussion:
             The POP3 server marks the message as deleted.  Any future
             reference to the message-number associated with the message
             in a POP3 command generates an error.  The POP3 server does
             not actually delete the message until the POP3 session
             enters the UPDATE state.

         Possible Responses:
             +OK message deleted
             -ERR no such message

         Examples:
             C: DELE 1
             S: +OK message 1 deleted
                ...
             C: DELE 2
             S: -ERR message 2 already deleted

      NOOP

         Arguments: none




Myers & Rose                                                    [Page 9]

RFC 1725                          POP3                     November 1994


         Restrictions:
             may only be given in the TRANSACTION state

         Discussion:
             The POP3 server does nothing, it merely replies with a
             positive response.

         Possible Responses:
             +OK

         Examples:
             C: NOOP
             S: +OK

      RSET

         Arguments: none

         Restrictions:
             may only be given in the TRANSACTION state

         Discussion:
             If any messages have been marked as deleted by the POP3
             server, they are unmarked.  The POP3 server then replies
             with a positive response.

         Possible Responses:
             +OK

         Examples:
             C: RSET
             S: +OK maildrop has 2 messages (320 octets)

6. The UPDATE State

   When the client issues the QUIT command from the TRANSACTION state,
   the POP3 session enters the UPDATE state.  (Note that if the client
   issues the QUIT command from the AUTHORIZATION state, the POP3
   session terminates but does NOT enter the UPDATE state.)

   If a session terminates for some reason other than a client-issued
   QUIT command, the POP3 session does NOT enter the UPDATE state and
   MUST not remove any messages from the maildrop.

      QUIT

         Arguments: none




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RFC 1725                          POP3                     November 1994


         Restrictions: none

         Discussion:
             The POP3 server removes all messages marked as deleted from
             the maildrop.  It then releases any exclusive-access lock
             on the maildrop and replies as to the status of these
             operations.  The TCP connection is then closed.

         Possible Responses:
             +OK

         Examples:
             C: QUIT
             S: +OK dewey POP3 server signing off (maildrop empty)
                ...
             C: QUIT
             S: +OK dewey POP3 server signing off (2 messages left)
                ...

7. Optional POP3 Commands

   The POP3 commands discussed above must be supported by all minimal
   implementations of POP3 servers.

   The optional POP3 commands described below permit a POP3 client
   greater freedom in message handling, while preserving a simple POP3
   server implementation.

      NOTE: This memo STRONGLY encourages implementations to support
      these commands in lieu of developing augmented drop and scan
      listings.  In short, the philosophy of this memo is to put
      intelligence in the part of the POP3 client and not the POP3
      server.

      TOP msg n

         Arguments:
             a message-number (required) which may NOT refer to to a
             message marked as deleted, and a non-negative number
             (required)

         Restrictions:
             may only be given in the TRANSACTION state

         Discussion:
             If the POP3 server issues a positive response, then the
             response given is multi-line.  After the initial +OK, the
             POP3 server sends the headers of the message, the blank



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RFC 1725                          POP3                     November 1994


             line separating the headers from the body, and then the
             number of lines indicated message's body, being careful to
             byte-stuff the termination character (as with all multi-
             line responses).

             Note that if the number of lines requested by the POP3
             client is greater than than the number of lines in the
             body, then the POP3 server sends the entire message.

         Possible Responses:
             +OK top of message follows
             -ERR no such message

         Examples:
             C: TOP 1 10
             S: +OK
             S: <the POP3 server sends the headers of the
                message, a blank line, and the first 10 lines
                of the body of the message>
             S: .
                ...
             C: TOP 100 3
             S: -ERR no such message

      UIDL [msg]

      Arguments:
          a message-number (optionally)  If a message-number is given,
          it may NOT refer to a message marked as deleted.

      Restrictions:
          may only be given in the TRANSACTION state.

      Discussion:
          If an argument was given and the POP3 server issues a positive
          response with a line containing information for that message.
          This line is called a "unique-id listing" for that message.

          If no argument was given and the POP3 server issues a positive
          response, then the response given is multi-line.  After the
          initial +OK, for each message in the maildrop, the POP3 server
          responds with a line containing information for that message.
          This line is called a "unique-id listing" for that message.

          In order to simplify parsing, all POP3 servers are required to
          use a certain format for unique-id listings.  A unique-id
          listing consists of the message-number of the message,
          followed by a single space and the unique-id of the message.



Myers & Rose                                                   [Page 12]

RFC 1725                          POP3                     November 1994