Comment 25 for bug 52667

Created an attachment (id=192713)
Adds mailnews.clobber_list_reply pref to turn Reply All into Reply To List

This is a first draft at providing a solution to this problem. It looks at the
headers of the mail being responded to, and if it doesn't see a
Mail-Followup-To header (the 'correct' way to achieve Reply To List as I
understand it), it checks for a List-Post or X-Mailing-List header. If it
finds one, it fakes up a Mail-Followup-To header which is then used as the
single recipient when doing a Reply-All.

Likewise, in the absence of a Mail-Reply-To header, it tries to second guess
based on Reply-To, X-Reply-To, From when doing a straight Reply (think
Reply-To-Sender in this instance). If the faked Mail-Followup-To is the same
as Reply-To, then a Mail-Reply-To is faked up from X-Reply-To or From
respectively.

This seems to have the desired effect for most common mailinglist software, at
the cost of turning the Reply To and Reply To All buttons silently into Reply
To Sender and Reply To List buttons in scenario. I personally think this makes
sense, however.

This behaviour is enableable through the mailnews.clobber_list_reply preference
in user.js.