Page Navigation:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79
Printable Version: RFC2821.PDF
RFC 2821 Simple Mail Transfer Protocol April 2001
The SMTP server transforms the command arguments by moving its own
identifier (its domain name or that of any domain for which it is
acting as a mail exchanger), if it appears, from the forward-path to
the beginning of the reverse-path.
Notice that the forward-path and reverse-path appear in the SMTP
commands and replies, but not necessarily in the message. That is,
there is no need for these paths and especially this syntax to appear
in the "To:" , "From:", "CC:", etc. fields of the message header.
Conversely, SMTP servers MUST NOT derive final message delivery
information from message header fields.
When the list of hosts is present, it is a "reverse" source route and
indicates that the mail was relayed through each host on the list
(the first host in the list was the most recent relay). This list is
used as a source route to return non-delivery notices to the sender.
As each relay host adds itself to the beginning of the list, it MUST
use its name as known in the transport environment to which it is
relaying the mail rather than that of the transport environment from
which the mail came (if they are different).
D. Scenarios
This section presents complete scenarios of several types of SMTP
sessions. In the examples, "C:" indicates what is said by the SMTP
client, and "S:" indicates what is said by the SMTP server.
D.1 A Typical SMTP Transaction Scenario
This SMTP example shows mail sent by Smith at host bar.com, to Jones,
Green, and Brown at host foo.com. Here we assume that host bar.com
contacts host foo.com directly. The mail is accepted for Jones and
Brown. Green does not have a mailbox at host foo.com.
S: 220 foo.com Simple Mail Transfer Service Ready
C: EHLO bar.com
S: 250-foo.com greets bar.com
S: 250-8BITMIME
S: 250-SIZE
S: 250-DSN
S: 250 HELP
C: MAIL FROM:
S: 250 OK
C: RCPT TO:
S: 250 OK
C: RCPT TO:
S: 550 No such user here
C: RCPT TO:
Klensin Standards Track [Page 73]