[Mimedefang] Two Subject lines in header

[Chris Carey]

I received a spam message today that the subject line was not tagged.
Investigating the header I found why.

"Subject" was specified twice. MIMEDefang only modifed the first "Subject" line.

MIMEDefang modified the *first* subject with "[spam 15 hits]", but the
second remained unchanged. Mozilla Thunderbird chose to use the second
unchanged subject line as the one to show. Having "Subject" twice in
the email headers seems to be a way to get spam to arrive in someones
inbox without client-side rules catching it..

So the obvious question - How to have MIMEDefang catch when Subject is
specified twice (or more) in the header?

--
Chris Carey