Bug: does not handle resent messages

[sebbASF]

As per RFC 2822, an original message can be resent to the same mailing list.

This message must have the following headers prefixed to it: Resent-From: Resent-Date: It should also have the following: Resent-Message-ID: It may have other headers added (see the RFC)

At present, these headers are not used.

Since the rest of the resent message is the same, failure to take account of the headers may mean that the original and new message are given the same database id; i.e. only one of them will be stored.

If the Resent-Message-ID: is present, that should perhaps be used instead of the original message-id when generating the database id. However the orginal M-Id needs to be kept for searches.

There is at least one example in the ASF archives, see: INFRA-15174

[sebbASF]

More examples: http://mail-archives.apache.org/mod_mbox/perl-embperl/201709.mbox

Also: tamaya.apache.org/dev/201709 perl.apache.org/embperl/201709