3.48. What about setting a "Reply-To:" header for the list?
Generally speaking, the Mailman developers consider this to be a bad idea, see http://www.unicom.com/pw/reply-to-harmful.html (written by Chip Rosenthal). The standard counter response from Simon Hill was originally posted at http://www.metasystema.org/essays/reply-to-useful.mhtml, was moved to http://www.metasystema.net/essays/reply-to.mhtml and can now be found at http://marc.merlins.org/netrants/reply-to-useful.html. There are also rebuttals to Simon Hill linked from Marc Merlin's page at http://marc.merlins.org/netrants/listreplyto.html.
The Mailman developers strongly agree with Chip and Marc, and strongly disagree with Simon.
If you need specifics, let's turn to Barry Warsaw, the principal developer of Mailman. For a selection of his posts on this topic over the years, see:
Please note that these are just the messages I quickly found where Barry specifically mentioned the same URL, and which are found in the Mailman archives on mail.python.org.
Now, all that said, the Mailman developers also realise that not everyone will agree with this perspective, and that there are some cases where different behaviour may actually be appropriate (see ../How do I create a newsletter, announcement, or one-way list? for one example).
This is why Mailman gives you the option of setting an explicit "Reply-To:" header for your list.
Question: Okay, but I have a lot of users who want the "Reply-To:" header munged, and a lot of others who don't. Does Mailman allow per-user control over this?
Answer: No, not as of this writing (2004-11-13). Mailman is one of the most flexible mailing list management systems in the world, giving each individual subscriber more control over what messages they see, how they see them, etc... as compared to virtually any other known mailing list management system, but this is one feature that has not (yet) been implemented.
This would be a fairly significant change to the Mailman code. So far, no one has created a patch to provide this functionality which has been accepted by the Mailman developers. This feature has been requested a couple of times (see https://bugs.launchpad.net/mailman/+bug/266733 and https://bugs.launchpad.net/mailman/+bug/266717).
A while back, a prototype patch was created to try to address the issue (see http://mail.python.org/pipermail/mailman-users/2002-March/018145.html, http://mail.python.org/pipermail/mailman-developers/2002-March/011068.html, and http://mail.python.org/pipermail/mailman-developers/2003-April/015040.html). However, this patch was not accepted by the Mailman developers at the time, and so far no one else has had the time and sufficient interest in the problem to create a suitable patch which could be incorporated into the current mainstream Mailman source code tree.
If you would like to generate your own patch to create this feature, we'd love to have your submission. In that case, please use the Mailman Launchpad Patch tracker at https://bugs.launchpad.net/mailman/+filebug. Otherwise, there is little choice but to wait and hope that someone else will do so and that their submission will make it into the "Mailman 2.1-maint" branch, or that the Mailman developers will address this issue as part of the upcoming complete ground-up rewrite for Mailman 3.
Fundamentally, this problem really should be solved in the MUA. Some users want things one way, some want them another, and any attempt to try to fix this problem within the mailing list management software is, at best, a poor hack. A good MUA will give you the tools you need to fix this problem on the client end and will allow the maximum amount of per-user control over filtering, etc.... Examples include the command-line program "mutt" (commonly used on Unix and Unix-like OSes), and the GUI program Eudora (available for MacOS 9, Mac OS X, and various Microsoft OSes).
A different approach would be to have the client configure their account on the server so as to add this header to all appropriate incoming mail, using a tool such as procmail.
Converted from the Mailman FAQ Wizard
This is one of many Frequently Asked Questions.