From: Wietse Venema (no email)
Date: Wed Jul 02 2008 - 11:36:03 EDT
Lewis:
> Sendmail has no issues sending from the same node, so it's not likely to be a
> network related issue. (SNAT'd to the same address)
I suppose you didn't spot any specific differences in the way that
EMSP is being spoken, such as:
- ESMTP command PIPELINING (MAIL FROM+RCPT TO+DATA in one TCP packet)
> tcpdump shows the standard transfer for the first 2-3 secs, Syn => ACK =>ACK
> PUSH, then 2 minutes of outbound packets with no reply, then a couple of
> inbound push before a FIN following a suspected timeout length of 2 minutes.
> tcpsump on external interface of firewall is consistent with other dumps.
Try turning off PIPELINING for borked sites:
http://www.postfix.org/postconf.5.html#smtp_discard_ehlo_keywords
http://www.postfix.org/postconf.5.html#smtp_discard_ehlo_keyword_address_maps
Wietse
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