I previously wrote:-

will@connectcorp.net said:

...

Some of our subscribers are reporting receiving 2, 3, or even 4 copies of each post.

I've seen very occasional examples of this on our list running mailman 1.0. The headers show that the duplication is occurring at the point where mailman injects the message into the MTA for delivery to the list subscribers.

...

The injects were spread over a 5 or so minute period, with the last 2 (duplicated) injects done 2.5 minutes apart. The machine would have been quite heavily loaded around that time - there was a message still in the process of injection by mailman when the second arrived and a few messages in the mailq.

It appears this happens at times of high load and/or when the DNS is not very available. Suspicions are that mailman is retrying a submission that it thinks is timing out.

In an attempt to work round this I have stopped exim doing receipient address verification on the fly for incoming messages from mailman (the config line is receiver_verify_hosts = !127.0.0.1/8:0.0.0.0/0 ).

This, so far (one day), appears to have fixed the problem. However its early days yet.

Nigel.

-- [ Nigel Metheringham Nigel.Metheringham@VData.co.uk ] [ Phone: +44 1423 850000 Fax +44 1423 858866 ]