Author: Ian FREISLICH Date: To: Tom Kistner CC: exim-users Subject: Re: [exim] An interesting problem (apparent duplicate delivery)
> Ian Freislich wrote: >
> > This phenomenon doesn't appear to be confined to one server or to
> > a particular user and it happens to random messages (or at least I
> > haven't found a pattern yet).
>
> Do you use AV or spam scanning after DATA? If yes, the cause may be a
> post-data timeout on the sending host. Exim may then send his 220 to a
> dead channel and queue the message, while the sending host has timed out
> the SMTP session and will retry sending the message later.
>
> That would explain the randomness. It typically only happens when the
> machine is well-loaded.
Spam scanning happens on a different cluster of servers. AV happens
on the same server. The spamassassin timeout (in Exim) is 2 minutes,
but I haven't paid much attention to the clamav connection. I'll
add some debugging an see if that's taking too long.
Our spamd servers are pretty heavily loaded, but the interesting
thing is the the messages are _identicle_. If the above scenario
was happening, I'd at least expect different Recieved: headers from
our server.
