rfc771.txt

RFC 的详细文档！

   it does not understand how deliver locally, or both relay and reply
   (if the originating address is present) to the message, it should not
   accept it.

   There are enough differences in the transmission procedure that the
   relay server will use a distinct mail transfer protocol, separate
   from the file transfer protocol.

MAIL TRANSFER PROTOCOL

   The mail trasfer protocol to be used by the relay server and all TCP
   hosts is documented in reference [9].

CONNECTIVITY

   There are nine cases of mail exchange, the three by three matrix of
   (1) old-table NCP hosts, (2) new-table NCP hosts, (3) TCP hosts.
   There are also two transfer mechanisms:  file transfer and mail
   transfer.  The diagonal is easy, each type of host can exchange mail
   with other hosts of its type.  The other cases are more subtle.







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September 1980                                                   RFC 771
Mail Transition Plan                                                    



   An old-table NCP host is assumed to have a table with 32-bit physical
   addresses, but no flag bits.  It has NCP and file transfer.  It does
   not have the separate mail transfer protocol.

   An new-table NCP host is assumed to have a table with 32-bit physical
   addresses, and the flag bits.  It has NCP and file transfer.  It also
   has the new separate mail transfer.

   An TCP host is assumed to have a table with 32-bit physical
   addresses, and the flag bits.  It has the new separate mail transfer.
   It probably has a file transfer, but does not use it for mail.

   1. Old-table NCP to Old-table NCP

      This transfer is direct and uses the old mechanisms -- NCP and
      file transfer.

   2. New-table NCP to Old-table NCP

      This transfer is direct and uses the old mechanisms -- NCP and
      file transfer.

   3. TCP to Old-table NCP

      This transfer must use a relay server.  The first transfer (from
      the TCP host to the relay server) is via TCP and the mail transfer
      protocol.  The second transfer (from the relay server to the
      old-table NCP) is via NCP and file transfer protocol.

   4. Old-table NCP to New-table NCP

      This transfer is direct and uses the old mechanisms -- NCP and
      file transfer.

   5. New-table NCP to New-table NCP

      This transfer is done with the NCP and the mail transfer protocol,
      that is, using the old interprocess communication system and the
      new mail transmission scheme.

   6. TCP to New-table NCP

      This transfer must use a relay server.  The first transfer (from
      the TCP host to the relay server) is via TCP and the mail transfer
      protocol.  The second transfer (from the relay server to the
      new-table NCP) is via NCP and mail transfer protocol.




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RFC 771                                                   September 1980
                                                    Mail Transition Plan



   7. Old-table NCP to TCP

      This transfer must use a special relay server.  The first transfer
      (from the old-table NCP to the relay server) is via NCP and the
      file transfer protocol.  The second transfer (from the relay
      server to the TCP host) is via TCP and mail transfer protocol.
      This relay server must be special because the messages coming from
      the old-table NCP host will not have the destination host
      information in the command argument.  This relay server must have
      a list of registered TCP user mailboxes and their associated TCP
      host identifiers.  Since such a registry could be potentially
      large and frequently changing (and will grow as more TCP hosts
      come into existence) it will be necessary to limit the mailboxes
      on the registry.

   8. New-table NCP to TCP

      This transfer must use a relay server.  The first transfer (from
      the new-table NCP to the relay server) is via NCP and the mail
      transfer protocol.  The second transfer (from the relay server to
      the TCP host) is via TCP and mail transfer protocol.

   9. TCP to TCP

      This transfer is direct and uses the new mechanisms -- TCP and the
      mail transfer protocol.

   In general, whenever possible the new procedures are to be used.

MULTIPLE RECIPIENTS

   A substantial portion of the mail sent is addressed to multiple
   recipients.  It would substantially cut the transmission and
   processing costs if such multiple recipient mail were transfered
   using the multiple recipient technique available for use in both the
   old file transfer protocol [12] and new mail transfer protocol [9].

   The relay servers will attempt to use a multiple recipient commands
   whenever applicable on transmitting messages, and will accept such
   commands when revceiving messages.










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September 1980                                                   RFC 771
Mail Transition Plan                                                    



COMPOSITION AND READING PROGRAMS

   The impact on the mail composition and reading programs is minimal.
   If these programs use a table to recognize, complete, or verify host
   identifiers, then they must be modified to use the new table.

   To assist the user in replying to messages it will be important that
   all addresses in the header fields (TO:, CC:, etc.) be complete with
   both the mailbox and host parts.  In some cases this has not
   previously been necessary since the addresses without host parts
   could be assumed to be local to the originating host, and the sending
   host was recorded by the receiving host.  When the messages were sent
   directly the originating host was the sending host, but when messages
   are relayed the originating host will not be the host sending the
   mail to the destination host.



































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RFC 771                                                   September 1980
                                                    Mail Transition Plan



REFERENCES

   [1]     Cerf, V., "The Catenet Model for Internetworking," IEN 48,
           DARPA/IPTO, July 1978.

   [2]     Postel, J., "Internet Protocol," RFC 760, USC/Information
           Sciences Institute, NTIS ADA079730, January 1980.

   [3]     Postel, J., "Transmission Control Protocol," RFC 761,
           USC/Information Sciences Institute, NTIS ADA082609,
           January 1980.

   [4]     Postel, J., "Telnet Protocol Specification," RFC 764,
           USC/Information Sciences Institute, June 1980.

   [4]     Postel, J., "File Transfer Protocol," RFC 765,
           USC/Information Sciences Institute, June 1980.

   [5]     Postel, J., "Assigned Numbers," USC/Information Sciences
           Institute, RFC 762, January 1980.

   [6]     Postel, J., "Internet Protocol Handbook," USC/Information
           Sciences Institute, RFC 766, July 1980.

   [7]     Feinler, E. and, J. Postel, "ARPANET Protocol Handbook,"
           NIC 7104, Network Information Center, SRI International,
           January 1978.

   [8]     Crocker, D., J. Vittal, K. Pogran, and, D. Henderson,
           "Standards for the Format of ARPA Network Text Messages,"
           RFC 733 7104, Network Information Center, SRI International,
           November 1977.

   [9]     Sluizer, S. and, J. Postel, "Mail Transfer Protocol,"
           USC/Information Sciences Institute, RFC rrr, September 1980.

   [10]    Postel, J., "Internet Message Protocol," USC/Information
           Sciences Institute, RFC 759, August 1980.

   [11]    Postel, J., "A Structured Format for Transmission of
           Multi-Media Documents," USC/Information Sciences Institute,
           RFC 767, August 1980.

   [12]    Harrenstien, K., "FTP Extension: XRSQ/XRCP,"
           SRI International, RFC 743, December 1977.





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