rfc821 (7 of 8)
ron at brl-adm.UUCP
ron at brl-adm.UUCP
Mon May 19 14:00:20 AEST 1986
RFC 821 August 1982
Simple Mail Transfer Protocol
Doing the preceding scenario more efficiently.
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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 at SU-SCORE.ARPA>
S: SOML FROM:<EAK at MIT-MC.ARPA>
R: 250 OK
S: RCPT TO:<Admin.MRC at 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
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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.
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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 at MIT-MC.ARPA>
R: 250-Fred Fonebone <Fonebone at USC-ISIQ.ARPA>
R: 250-Xenon Y. Zither <XYZ at MIT-AI.ARPA>
R: 250-Quincy Smith <@USC-ISIF.ARPA:Q-Smith at ISI-VAXA.ARPA>
R: 250-<joe at foo-unix.ARPA>
R: 250 <xyz at 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 at MIT-MC.ARPA>
R: 250-<XYZ at MIT-AI.ARPA>
R: 250-Quincy Smith <@USC-ISIF.ARPA:Q-Smith at ISI-VAXA.ARPA>
R: 250-<fred at BBN-UNIX.ARPA>
R: 250 <xyz at 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 at SU-SCORE.ARPA>
R: 250 OK
S: RCPT TO:<@USC-ISIE.ARPA:ABC at MIT-MC.ARPA>
R: 250 OK
S: RCPT TO:<@USC-ISIE.ARPA:Fonebone at USC-ISIQA.ARPA>
R: 250 OK
S: RCPT TO:<@USC-ISIE.ARPA:XYZ at MIT-AI.ARPA>
R: 250 OK
S: RCPT
TO:<@USC-ISIE.ARPA, at USC-ISIF.ARPA:Q-Smith at ISI-VAXA.ARPA>
R: 250 OK
S: RCPT TO:<@USC-ISIE.ARPA:joe at FOO-UNIX.ARPA>
R: 250 OK
S: RCPT TO:<@USC-ISIE.ARPA:xyz at BAR-UNIX.ARPA>
R: 250 OK
S: RCPT TO:<@USC-ISIE.ARPA:fred at 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
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[Page 60] Postel
RFC 821 August 1982
Simple Mail Transfer Protocol
Forwarding Scenarios
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R: 220 USC-ISIF.ARPA Simple Mail Transfer Service Ready
S: HELO LBL-UNIX.ARPA
R: 250 USC-ISIF.ARPA
S: MAIL FROM:<mo at LBL-UNIX.ARPA>
R: 250 OK
S: RCPT TO:<fred at USC-ISIF.ARPA>
R: 251 User not local; will forward to <Jones at 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
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Postel [Page 61]
August 1982 RFC 821
Simple Mail Transfer Protocol
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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 at LBL-UNIX.ARPA>
R: 250 OK
S: RCPT TO:<fred at USC-ISIF.ARPA>
R: 251 User not local; will forward to <Jones at 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 at LBL-UNIX.ARPA>
R: 250 OK
S: RCPT TO:<Jones at 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
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[Page 62] Postel
RFC 821 August 1982
Simple Mail Transfer Protocol
Too Many Recipients Scenario
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R: 220 BERKELEY.ARPA Simple Mail Transfer Service Ready
S: HELO USC-ISIF.ARPA
R: 250 BERKELEY.ARPA
S: MAIL FROM:<Postel at USC-ISIF.ARPA>
R: 250 OK
S: RCPT TO:<fabry at BERKELEY.ARPA>
R: 250 OK
S: RCPT TO:<eric at 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 at USC-ISIF.ARPA>
R: 250 OK
S: RCPT TO:<eric at 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 at 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
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