Strange persistant 'timeout after DATA' from mail2.bund.de

11 msg	Reject unknown Sender address
10 msg	Postfix and archiving
5 msg	-o content_filter overrides main.cf ?
1 msg	Postfix 2.4.3 and 2.3.11 available
8 msg	SASL authentication via dovecot?
2 msg	postfix/sasl: sql_select option missing - wtf?
3 msg	max connection rate/count/limit issues.
1 msg	requeue mails
6 msg	nothing in maillog
9 msg	local and remote storage for same user
7 msg	Rejecting Invaliud Users - Useful Resource poin...
4 msg	Distributing map files
5 msg	relay_recipient_maps for multiple destinations
13 msg	auto-responders with postfix
6 msg	Mydestination with virtual domains
6 msg	Splitting smtpd_proxy_filter in smtpd_recipient...
10 msg	Can't Send to Sprint Messaging Users..
1 msg	MAAWG meeting anyone?
2 msg	basic postfix 2.4.1 configuration for a simple ...

Strange persistant 'timeout after DATA' from ma...
\ lst_hoe01 (30 May 2007)
. \ (Wietse Venema) (30 May 2007)
. . \ lst_hoe01 (30 May 2007)
. . . \ (Wietse Venema) (30 May 2007)
. . . . \ lst_hoe01 (30 May 2007)

Subject:	Strange persistant 'timeout after DATA' from mail2.bund.de
Group:	Postfix-users
From:	lst_hoe01
Date:	30 May 2007

Hello

Last weekend we discovered that we get repeatedly "timeout after DATA"
from one remote location. To find out the problem we captured a
tcpdump which is attached as plain-text export in the ZIP-file (e-Mail
addresses
munged to protect the innocent).
The error occurs after our Postfix 2.4.1 send "250 2.1.5 Ok" (packet
12). The remote sent a ACK and nothing more until the connection
timeout from our site. After Postfix try to close the connection the
remote site start to sent the message body...

What we have tried so far :
- Raise the timeout from 15 sec to 35 sec -> No change
- Disable tcp_window_scaling -> No change
- Disable ESMTP extension with smtpd_discard_ehlo_keywords_maps -> No change

As the remote site is some more important site (German goverment) we
like to fix the problem.

Thanxs for any help

Andreas