> -----Original Message----- > From: owner-postfix-us...@postfix.org > [mailto:owner-postfix-us...@postfix.org] On Behalf Of Victor Duchovni > Sent: Wednesday, 20 May 2009 6:19 PM > To: postfix-users@postfix.org > Subject: Re: Query re logs > > On Wed, May 20, 2009 at 02:44:57PM +1000, MacShane, Tracy wrote: > > > May 20 10:27:25 smtp3 postfix/smtpd[17136]: > > > dfw-mailout1.example.com[199.xxx.xxx.xx]: 421 4.4.2 > > smtp3.ourdomain.example.net Error: timeout exceeded > > What I see for the same host is just overly-aggressive > connection caching, they hold idle connections open for 120s > after ".": > ... > The evidence that the problem is on their end is not yet in > hand. Either side could have path MTU issues, window-scaling > issues, ... with some insufficiently robust or slightly > misconfigured firewall. > ...
Great, thanks very much for the investigation, illumination re connection caching and timeout after EOM, and the suggestions for further analysis. I did have a notion that there could be some strange firewall problem going on at either or both ends (as you say, Sendmail should be reliable), so I didn't want to jump to any conclusions that we were exempt from any issues. I'll get them to directly send me some test emails tomorrow and I'll go through tcpdump to see what eventuates. We certainly have no problem receiving messages *without* attachments from them or ~400KB messages with or without Word attachments from elsewhere. I also want to exclude whether message format (they may be sending "rich text") might having some kind of synergistic effect as well.
