I have a Postfix mail server handling mail relay for web sites. It's working perfectly and delivering hundreds of mails every day without issues.
In the past few months, there have been 4 occurances where the same mail is delivered over 100 times to the same e-mail address.
After researching I noticed that all messages have the same message id so they are only being sent once from the web server and all recipients are hosted on plus.net mail servers.
The only thing I can do is to remove the message manually from the postqueue.
Here are two exaamples from the log (with actual e-mail address removed):
Dec 12 11:28:27 server1 postfix/smtp[18694]: 7333662B27: to=, relay=mx-trial.core.plus.net[212.159.8.200]:25, delay=246505, delays=245300/0.02/605/600, dsn=4.4.2, status=deferred (conversation with mx-trial.core.plus.net[212.159.8.200] timed out while sending end of data -- message may be sent more than once)
Oct 26 07:24:06 server1 postfix/smtp[4074]: 2BBD260FCE: to=, relay=mx.avasin.plus.net[212.159.9.200]:25, delay=214049, delays=212842/0.12/606/600, dsn=4.4.2, status=deferred (conversation with mx.avasin.plus.net[212.159.9.200] timed out while sending end of data -- message may be sent more than once)
Any ideas? Looks like it's timing out problably after 60 seconds. That doesn't seem to be issue for other mail servers.
Is this a known issue with plus.net? Is there anything I can do to avoid the timeout? Can I somehow configure Postfix to not resend when receiving timeouts from plus.net?
