Victoriano Giralt:
> Wireshark shows "TCP window full" several times while Postfix is
> dutifully trying to send the messages and finally the connection is
> reset at TCP level.
This may be the infamous window scaling problem. See below for
workaround.
Wietse
POSTCONF(5) POSTCONF(5)
...
tcp_windowsize (default: 0)
An optional workaround for routers that break TCP window scaling.
Specify a value > 0 and < 65536 to enable this feature. With Postfix
TCP servers (smtpd(8), qmqpd(8)), this feature is implemented by the
Postfix master(8) daemon.
To change this parameter without stopping Postfix, [steps deleted]
If you skip these steps with a running Postfix system, then the
tcp_windowsize change will work only for Postfix TCP clients (smtp(8),
lmtp(8)).
This feature is available in Postfix 2.6 and later.
