smtp timeout errors

[Taldon]

We have a customer that keeps trying to email us and gets back an error, "Error reading SMTP packet; response to dot-stuffed message expected"
I am also seeing quite a few smtp timeout messages in the syslog, but none specifically matching the time and sender of our customer.

What is causing the mail from just this one customer to not reach us, and does it have anything to do with the timeouts? How can I fix it?

info: Postfix 20010228-pl03 on Linux, mandrake 8.1. Hardware: dual 733mhz P3, 1gig ram, 100mb/full duplex nic, 21gb-RAID5

Any help is appreciated.
T

 

[Taldon]

updating this with some info I found on another forum site...

and I guess I should have mentioned we are behind a PIX firewall.


/blatant rip of someone's post from somewhere else...
PIX - bingo. I had the same symptoms - repeat emails, deferrals, dead
connections. If you run the PIX with smtp fixup enabled, the PIX rewrites
qmail's "message queued" response such that some foreign clients do not
understand that the message has actually been queued, despite the fact
that it has. Remote MTAs just keep waiting for a response, and eventually
timeout. Qmail has already queued the mail, but the remote servers just
keep trying - that's why you're seeing so many duplicates.

If you trust the security of qmail (reasonably safe assumption), just
disable smtp fixup on the PIX, and your problem should disappear entirely.
/end of rip


so, does anyone know if this is really what is happening here? The PIX documentation and forums all suggest using the "fixup smtp" statement in order to clear up some other potential problems.