On Tue, 10 Aug 2010, John Levine wrote:
Tail end of section 6.1 of 5321:
"To avoid receiving duplicate messages as the result of timeouts, a
receiver-SMTP MUST seek to minimize the time required to respond to
the final <CRLF>.<CRLF> end of data indicator. "
That language is taken verbatim from 2821. In both RFCs the following
sentence refers to RFC 1047.
And RFC 2821 took it from 1123 :-)
RFCs 1123 et seq. also say "When the receiver gets the final period
terminating the message data, it typically performs processing to deliver
the message to a user mailbox" and RFC 1047 mentions specific problems
related to mailing list expansion.
In my experience mailers don't do delivery during the incoming SMTP
conversation, which sounds like a significant change relative to the
problematic mailers of the late 1980s.
(It would be OK to do delivery during the incoming conversation if it
can be sufficiently decoupled that a slow delivery doesn't delay the
server's <CRLF>.<CRLF> reply longer than some upper bound and the
delivery continues while the client moves on.)
Tony.
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BAILEY: NORTHWEST 4 OR 5. SLIGHT OR MODERATE. SHOWERS. GOOD.