[Merge] lp:~mss/mailman/3.0-smtp-log-fix into lp:mailman

[Barry Warsaw]

Thanks for the patch.  I'm going to try to write a test for this, but can you tell me in what situation you're seeing the None's?  Having a Message-ID header should be a requirement once the message is in the system, so if there are entry points which don't ensure that header, it might be better (or at least *also*) to fix that.
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https://code.launchpad.net/~mss/mailman/3.0-smtp-log-fix/+merge/55760
Your team Mailman Coders is requested to review the proposed merge of lp:~mss/mailman/3.0-smtp-log-fix into lp:mailman.