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

[Malte S. Stretz]

I just tested mailman by speaking via netcat to the LMTP port.  And I was too lazy to type a Message-Id header.

I think it should be fine to refuse the mail if there Message-Id header is missing (the mda should have added one already).
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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.