brian@sdcsvax.UCSD.EDU (Brian Kantor) (08/28/87)
-- [Page 50] Postel RFC 821 August 1982 Simple Mail Transfer Protocol APPENDIX F Scenarios This section presents complete scenarios of several types of SMTP sessions. A Typical SMTP Transaction Scenario This SMTP example shows mail sent by Smith at host USC-ISIF, to Jones, Green, and Brown at host BBN-UNIX. Here we assume that host USC-ISIF contacts host BBN-UNIX directly. The mail is accepted for Jones and Brown. Green does not have a mailbox at host BBN-UNIX. ------------------------------------------------------------- R: 220 BBN-UNIX.ARPA Simple Mail Transfer Service Ready S: HELO USC-ISIF.ARPA R: 250 BBN-UNIX.ARPA S: MAIL FROM:<Smith@USC-ISIF.ARPA> R: 250 OK S: RCPT TO:<Jones@BBN-UNIX.ARPA> R: 250 OK S: RCPT TO:<Green@BBN-UNIX.ARPA> R: 550 No such user here S: RCPT TO:<Brown@BBN-UNIX.ARPA> R: 250 OK S: DATA R: 354 Start mail input; end with <CRLF>.<CRLF> S: Blah blah blah... S: ...etc. etc. etc. S: . R: 250 OK S: QUIT R: 221 BBN-UNIX.ARPA Service closing transmission channel Scenario 1 ------------------------------------------------------------- Postel [Page 51] August 1982 RFC 821 Simple Mail Transfer Protocol Aborted SMTP Transaction Scenario ------------------------------------------------------------- R: 220 MIT-Multics.ARPA Simple Mail Transfer Service Ready S: HELO ISI-VAXA.ARPA R: 250 MIT-Multics.ARPA S: MAIL FROM:<Smith@ISI-VAXA.ARPA> R: 250 OK S: RCPT TO:<Jones@MIT-Multics.ARPA> R: 250 OK S: RCPT TO:<Green@MIT-Multics.ARPA> R: 550 No such user here S: RSET R: 250 OK S: QUIT R: 221 MIT-Multics.ARPA Service closing transmission channel Scenario 2 ------------------------------------------------------------- [Page 52] Postel RFC 821 August 1982 Simple Mail Transfer Protocol Relayed Mail Scenario ------------------------------------------------------------- Step 1 -- Source Host to Relay Host R: 220 USC-ISIE.ARPA Simple Mail Transfer Service Ready S: HELO MIT-AI.ARPA R: 250 USC-ISIE.ARPA S: MAIL FROM:<JQP@MIT-AI.ARPA> R: 250 OK S: RCPT TO:<@USC-ISIE.ARPA:Jones@BBN-VAX.ARPA> R: 250 OK S: DATA R: 354 Start mail input; end with <CRLF>.<CRLF> S: Date: 2 Nov 81 22:33:44 S: From: John Q. Public <JQP@MIT-AI.ARPA> S: Subject: The Next Meeting of the Board S: To: Jones@BBN-Vax.ARPA S: S: Bill: S: The next meeting of the board of directors will be S: on Tuesday. S: John. S: . R: 250 OK S: QUIT R: 221 USC-ISIE.ARPA Service closing transmission channel Postel [Page 53] August 1982 RFC 821 Simple Mail Transfer Protocol Step 2 -- Relay Host to Destination Host R: 220 BBN-VAX.ARPA Simple Mail Transfer Service Ready S: HELO USC-ISIE.ARPA R: 250 BBN-VAX.ARPA S: MAIL FROM:<@USC-ISIE.ARPA:JQP@MIT-AI.ARPA> R: 250 OK S: RCPT TO:<Jones@BBN-VAX.ARPA> R: 250 OK S: DATA R: 354 Start mail input; end with <CRLF>.<CRLF> S: Received: from MIT-AI.ARPA by USC-ISIE.ARPA ; 2 Nov 81 22:40:10 UT S: Date: 2 Nov 81 22:33:44 S: From: John Q. Public <JQP@MIT-AI.ARPA> S: Subject: The Next Meeting of the Board S: To: Jones@BBN-Vax.ARPA S: S: Bill: S: The next meeting of the board of directors will be S: on Tuesday. S: John. S: . R: 250 OK S: QUIT R: 221 USC-ISIE.ARPA Service closing transmission channel Scenario 3 ------------------------------------------------------------- [Page 54] Postel RFC 821 August 1982 Simple Mail Transfer Protocol Verifying and Sending Scenario ------------------------------------------------------------- R: 220 SU-SCORE.ARPA Simple Mail Transfer Service Ready S: HELO MIT-MC.ARPA R: 250 SU-SCORE.ARPA S: VRFY Crispin R: 250 Mark Crispin <Admin.MRC@SU-SCORE.ARPA> S: SEND FROM:<EAK@MIT-MC.ARPA> R: 250 OK S: RCPT TO:<Admin.MRC@SU-SCORE.ARPA> R: 250 OK S: DATA R: 354 Start mail input; end with <CRLF>.<CRLF> S: Blah blah blah... S: ...etc. etc. etc. S: . R: 250 OK S: QUIT R: 221 SU-SCORE.ARPA Service closing transmission channel Scenario 4 ------------------------------------------------------------- Postel [Page 55] August 1982 RFC 821 Simple Mail Transfer Protocol Sending and Mailing Scenarios First the user's name is verified, then an attempt is made to send to the user's terminal. When that fails, the messages is mailed to the user's mailbox. ------------------------------------------------------------- R: 220 SU-SCORE.ARPA Simple Mail Transfer Service Ready S: HELO MIT-MC.ARPA R: 250 SU-SCORE.ARPA S: VRFY Crispin R: 250 Mark Crispin <Admin.MRC@SU-SCORE.ARPA> S: SEND FROM:<EAK@MIT-MC.ARPA> R: 250 OK S: RCPT TO:<Admin.MRC@SU-SCORE.ARPA> R: 450 User not active now S: RSET R: 250 OK S: MAIL FROM:<EAK@MIT-MC.ARPA> R: 250 OK S: RCPT TO:<Admin.MRC@SU-SCORE.ARPA> R: 250 OK S: DATA R: 354 Start mail input; end with <CRLF>.<CRLF> S: Blah blah blah... S: ...etc. etc. etc. S: . R: 250 OK S: QUIT R: 221 SU-SCORE.ARPA Service closing transmission channel Scenario 5 ------------------------------------------------------------- [Page 56] Postel RFC 821 August 1982 Simple Mail Transfer Protocol Doing the preceding scenario more efficiently. ------------------------------------------------------------- R: 220 SU-SCORE.ARPA Simple Mail Transfer Service Ready S: HELO MIT-MC.ARPA R: 250 SU-SCORE.ARPA S: VRFY Crispin R: 250 Mark Crispin <Admin.MRC@SU-SCORE.ARPA> S: SOML FROM:<EAK@MIT-MC.ARPA> R: 250 OK S: RCPT TO:<Admin.MRC@SU-SCORE.ARPA> R: 250 User not active now, so will do mail. S: DATA R: 354 Start mail input; end with <CRLF>.<CRLF> S: Blah blah blah... S: ...etc. etc. etc. S: . R: 250 OK S: QUIT R: 221 SU-SCORE.ARPA Service closing transmission channel Scenario 6 ------------------------------------------------------------- Postel [Page 57] August 1982 RFC 821 Simple Mail Transfer Protocol Mailing List Scenario First each of two mailing lists are expanded in separate sessions with different hosts. Then the message is sent to everyone that appeared on either list (but no duplicates) via a relay host. ------------------------------------------------------------- Step 1 -- Expanding the First List R: 220 MIT-AI.ARPA Simple Mail Transfer Service Ready S: HELO SU-SCORE.ARPA R: 250 MIT-AI.ARPA S: EXPN Example-People R: 250-<ABC@MIT-MC.ARPA> R: 250-Fred Fonebone <Fonebone@USC-ISIQ.ARPA> R: 250-Xenon Y. Zither <XYZ@MIT-AI.ARPA> R: 250-Quincy Smith <@USC-ISIF.ARPA:Q-Smith@ISI-VAXA.ARPA> R: 250-<joe@foo-unix.ARPA> R: 250 <xyz@bar-unix.ARPA> S: QUIT R: 221 MIT-AI.ARPA Service closing transmission channel [Page 58] Postel RFC 821 August 1982 Simple Mail Transfer Protocol Step 2 -- Expanding the Second List R: 220 MIT-MC.ARPA Simple Mail Transfer Service Ready S: HELO SU-SCORE.ARPA R: 250 MIT-MC.ARPA S: EXPN Interested-Parties R: 250-Al Calico <ABC@MIT-MC.ARPA> R: 250-<XYZ@MIT-AI.ARPA> R: 250-Quincy Smith <@USC-ISIF.ARPA:Q-Smith@ISI-VAXA.ARPA> R: 250-<fred@BBN-UNIX.ARPA> R: 250 <xyz@bar-unix.ARPA> S: QUIT R: 221 MIT-MC.ARPA Service closing transmission channel Postel [Page 59] August 1982 RFC 821 Simple Mail Transfer Protocol Step 3 -- Mailing to All via a Relay Host R: 220 USC-ISIE.ARPA Simple Mail Transfer Service Ready S: HELO SU-SCORE.ARPA R: 250 USC-ISIE.ARPA S: MAIL FROM:<Account.Person@SU-SCORE.ARPA> R: 250 OK S: RCPT TO:<@USC-ISIE.ARPA:ABC@MIT-MC.ARPA> R: 250 OK S: RCPT TO:<@USC-ISIE.ARPA:Fonebone@USC-ISIQA.ARPA> R: 250 OK S: RCPT TO:<@USC-ISIE.ARPA:XYZ@MIT-AI.ARPA> R: 250 OK S: RCPT TO:<@USC-ISIE.ARPA,@USC-ISIF.ARPA:Q-Smith@ISI-VAXA.ARPA> R: 250 OK S: RCPT TO:<@USC-ISIE.ARPA:joe@FOO-UNIX.ARPA> R: 250 OK S: RCPT TO:<@USC-ISIE.ARPA:xyz@BAR-UNIX.ARPA> R: 250 OK S: RCPT TO:<@USC-ISIE.ARPA:fred@BBN-UNIX.ARPA> R: 250 OK S: DATA R: 354 Start mail input; end with <CRLF>.<CRLF> S: Blah blah blah... S: ...etc. etc. etc. S: . R: 250 OK S: QUIT R: 221 USC-ISIE.ARPA Service closing transmission channel Scenario 7 ------------------------------------------------------------- [Page 60] Postel RFC 821 August 1982 Simple Mail Transfer Protocol Forwarding Scenarios ------------------------------------------------------------- R: 220 USC-ISIF.ARPA Simple Mail Transfer Service Ready S: HELO LBL-UNIX.ARPA R: 250 USC-ISIF.ARPA S: MAIL FROM:<mo@LBL-UNIX.ARPA> R: 250 OK S: RCPT TO:<fred@USC-ISIF.ARPA> R: 251 User not local; will forward to <Jones@USC-ISI.ARPA> S: DATA R: 354 Start mail input; end with <CRLF>.<CRLF> S: Blah blah blah... S: ...etc. etc. etc. S: . R: 250 OK S: QUIT R: 221 USC-ISIF.ARPA Service closing transmission channel Scenario 8 ------------------------------------------------------------- Postel [Page 61] August 1982 RFC 821 Simple Mail Transfer Protocol ------------------------------------------------------------- Step 1 -- Trying the Mailbox at the First Host R: 220 USC-ISIF.ARPA Simple Mail Transfer Service Ready S: HELO LBL-UNIX.ARPA R: 250 USC-ISIF.ARPA S: MAIL FROM:<mo@LBL-UNIX.ARPA> R: 250 OK S: RCPT TO:<fred@USC-ISIF.ARPA> R: 251 User not local; will forward to <Jones@USC-ISI.ARPA> S: RSET R: 250 OK S: QUIT R: 221 USC-ISIF.ARPA Service closing transmission channel Step 2 -- Delivering the Mail at the Second Host R: 220 USC-ISI.ARPA Simple Mail Transfer Service Ready S: HELO LBL-UNIX.ARPA R: 250 USC-ISI.ARPA S: MAIL FROM:<mo@LBL-UNIX.ARPA> R: 250 OK S: RCPT TO:<Jones@USC-ISI.ARPA> R: OK S: DATA R: 354 Start mail input; end with <CRLF>.<CRLF> S: Blah blah blah... S: ...etc. etc. etc. S: . R: 250 OK S: QUIT R: 221 USC-ISI.ARPA Service closing transmission channel Scenario 9 ------------------------------------------------------------- [Page 62] Postel RFC 821 August 1982 Simple Mail Transfer Protocol Too Many Recipients Scenario ------------------------------------------------------------- R: 220 BERKELEY.ARPA Simple Mail Transfer Service Ready S: HELO USC-ISIF.ARPA R: 250 BERKELEY.ARPA S: MAIL FROM:<Postel@USC-ISIF.ARPA> R: 250 OK S: RCPT TO:<fabry@BERKELEY.ARPA> R: 250 OK S: RCPT TO:<eric@BERKELEY.ARPA> R: 552 Recipient storage full, try again in another transaction S: DATA R: 354 Start mail input; end with <CRLF>.<CRLF> S: Blah blah blah... S: ...etc. etc. etc. S: . R: 250 OK S: MAIL FROM:<Postel@USC-ISIF.ARPA> R: 250 OK S: RCPT TO:<eric@BERKELEY.ARPA> R: 250 OK S: DATA R: 354 Start mail input; end with <CRLF>.<CRLF> S: Blah blah blah... S: ...etc. etc. etc. S: . R: 250 OK S: QUIT R: 221 BERKELEY.ARPA Service closing transmission channel Scenario 10 ------------------------------------------------------------- Note that a real implementation must handle many recipients as specified in Section 4.5.3. Postel [Page 63] August 1982 RFC 821 Simple Mail Transfer Protocol GLOSSARY ASCII American Standard Code for Information Interchange [1]. command A request for a mail service action sent by the sender-SMTP to the receiver-SMTP. domain The hierarchially structured global character string address of a host computer in the mail system. end of mail data indication A special sequence of characters that indicates the end of the mail data. In particular, the five characters carriage return, line feed, period, carriage return, line feed, in that order. host A computer in the internetwork environment on which mailboxes or SMTP processes reside. line A a sequence of ASCII characters ending with a <CRLF>. mail data A sequence of ASCII characters of arbitrary length, which conforms to the standard set in the Standard for the Format of ARPA Internet Text Messages (RFC 822 [2]). mailbox A character string (address) which identifies a user to whom mail is to be sent. Mailbox normally consists of the host and user specifications. The standard mailbox naming convention is defined to be "user@domain". Additionally, the "container" in which mail is stored. [Page 64] Postel RFC 821 August 1982 Simple Mail Transfer Protocol receiver-SMTP process A process which transfers mail in cooperation with a sender-SMTP process. It waits for a connection to be established via the transport service. It receives SMTP commands from the sender-SMTP, sends replies, and performs the specified operations. reply A reply is an acknowledgment (positive or negative) sent from receiver to sender via the transmission channel in response to a command. The general form of a reply is a completion code (including error codes) followed by a text string. The codes are for use by programs and the text is usually intended for human users. sender-SMTP process A process which transfers mail in cooperation with a receiver-SMTP process. A local language may be used in the user interface command/reply dialogue. The sender-SMTP initiates the transport service connection. It initiates SMTP commands, receives replies, and governs the transfer of mail. session The set of exchanges that occur while the transmission channel is open. transaction The set of exchanges required for one message to be transmitted for one or more recipients. transmission channel A full-duplex communication path between a sender-SMTP and a receiver-SMTP for the exchange of commands, replies, and mail text. transport service Any reliable stream-oriented data communication services. For example, NCP, TCP, NITS. Postel [Page 65] August 1982 RFC 821 Simple Mail Transfer Protocol user A human being (or a process on behalf of a human being) wishing to obtain mail transfer service. In addition, a recipient of computer mail. word A sequence of printing characters. <CRLF> The characters carriage return and line feed (in that order). <SP> The space character. [Page 66] Postel RFC 821 August 1982 Simple Mail Transfer Protocol REFERENCES [1] ASCII ASCII, "USA Code for Information Interchange", United States of America Standards Institute, X3.4, 1968. Also in: Feinler, E. and J. Postel, eds., "ARPANET Protocol Handbook", NIC 7104, for the Defense Communications Agency by SRI International, Menlo Park, California, Revised January 1978. [2] RFC 822 Crocker, D., "Standard for the Format of ARPA Internet Text Messages," RFC 822, Department of Electrical Engineering, University of Delaware, August 1982. [3] TCP Postel, J., ed., "Transmission Control Protocol - DARPA Internet Program Protocol Specification", RFC 793, USC/Information Sciences Institute, NTIS AD Number A111091, September 1981. Also in: Feinler, E. and J. Postel, eds., "Internet Protocol Transition Workbook", SRI International, Menlo Park, California, March 1982. [4] NCP McKenzie,A., "Host/Host Protocol for the ARPA Network", NIC 8246, January 1972. Also in: Feinler, E. and J. Postel, eds., "ARPANET Protocol Handbook", NIC 7104, for the Defense Communications Agency by SRI International, Menlo Park, California, Revised January 1978. [5] Initial Connection Protocol Postel, J., "Official Initial Connection Protocol", NIC 7101, 11 June 1971. Also in: Feinler, E. and J. Postel, eds., "ARPANET Protocol Handbook", NIC 7104, for the Defense Communications Agency by SRI International, Menlo Park, California, Revised January 1978. [6] NITS PSS/SG3, "A Network Independent Transport Service", Study Group 3, The Post Office PSS Users Group, February 1980. Available from the DCPU, National Physical Laboratory, Teddington, UK. Postel [Page 67] August 1982 RFC 821 Simple Mail Transfer Protocol [7] X.25 CCITT, "Recommendation X.25 - Interface Between Data Terminal Equipment (DTE) and Data Circuit-terminating Equipment (DCE) for Terminals Operating in the Packet Mode on Public Data Networks," CCITT Orange Book, Vol. VIII.2, International Telephone and Telegraph Consultative Committee, Geneva, 1976. [Page 68] Postel