-----Original Message-----
From: Charles Gregory [mailto:cgreg...@hwcn.org]
Sent: donderdag 7 mei 2009 21:58
To: SpamAssassin Users List
Subject: Odd behaviour under load.
> Do yahoo and python.org enforce a shorter time-out?
Highly doubtful. RFC 2821, Section 4.5.3.2 ("Timeouts") gives you a 2
minutes window while awaiting the "354 Start Input" reply to a DATA
command. But please note that timeouts in this Section are a SHOULD, not
a MUST.
> Or does some characteristic of list mail make it take longer to
> process in sa?
Headers are part of the DATA stream. Hence, at the time a connecting
server is awaiting your "354 Start Input" reply to their DATA command, the
whole notion of a (possible) mailing-list is simply not within scope yet
(as the headers have not been received yet). At the start of DATA, you've
basically just concluded the envelope-stage of the SMTP dialogue (MAIL
FROM, RCPT TO, etc). So, whatever characteristic of list mail *might* make
things taking longer to process in SA, it's simply not yet relevant here.
If you're doing Milter-type SPF-lookups right after MAIL FROM, for
instance, you'd have a 5 minutes timeout window. Same after RCPT TO. But
since both those actions are completed by the time the connecting server
issues its DATA command, there's basically no valid reason for your server
to wait unusually long to respond with its 354 reply. Not unless it's very
broken, that is.
> At first I didn't associate this behaviour with SA because the
> duplicates were being sent by the originating system, not from within
> mine. I wasn't even certain that the fault was mine, given the way it
> mostly seemed to occur with certain list servers. The mail was getting
> delivered to my local recipient, but the sending system was resending
> a few minutes later (and would do so three or four times).
It's quite possible for a connecting mail server to retry after it
received, say, one of the many 4.x.x codes. However, what's definitely
broken in your setup is that, in such a scenario, apparently your LDA
already delivers (part of an) aborted mail. That seems too strange for
words; so, likely, you're not sending out proper reply codes to connecting
mail servers.
So, the solution is simple: fix your mail server; or have someone do it
for you.
- Mark
