From: Victor Duchovni (no email)
Date: Wed Dec 01 2004 - 08:36:40 EST
On Wed, Dec 01, 2004 at 02:18:43PM +0100, Ralph Utbult wrote:
> Hi,
>
> I'm running ML 10.0 with Postfix, Spamassassin & Mailman. Clients run
> Windows 2k with Outlook Express or Outlook. Ordinary mail is ok, but
> hook up an attachment and the client will never finish sending. Any idea?
>
The most common source of size dependent behaviour is PMTU discovery
failure. Make sure that any firewall between your Outlook users and the
server allow (and if necessary NAT) ICMP unreachable responses.
Send a large text message with no attachments and see if size rather
than MIME structure is the primary issue. Also consider disabling SMTP
inspection in any firewalls, they often get it wrong, Postfix is robust
enough to not require any help.
Show the server logs for aborted messages, and if provide a full
(complete packets with -s 1500), raw (the binary file with -w file, not
the decoded packets) tcpdump capture file of a single session.
A useful trick is:
tcpdump -r filein -w fileout tcp port 12345 or icmp host 1.2.3.4
to pick a particular session (with host 1.2.3.4 connecting with source
port 12345) out of a multi-session capture. Generate the original
capture via:
tcpdump -i interface -w filein tcp port 25 or icmp
-- Viktor. Disclaimer: off-list followups get on-list replies or get ignored. Please do not ignore the "Reply-To" header. To unsubscribe from the postfix-users list, visit http://www.postfix.org/lists.html or click the link below: <mailto:?body=unsubscribe%20postfix-users>
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