as many of you probably would agree, whether you munge the Reply-To headers or not, both ways are not perfect. Just today I had a hard time again, as I'm not happy with both options, and finally came up with some ideas how the situation could be improved, about which I would like to read your comments:
One of the problems not using Reply-To munging is, that by using the reply-to-all function of MUAs the list of receivers tends to accumulate. As in open lists the users cannot know, if an address is part of the list, they cannot just delete them without risking to drop people from the discussion. So what about an option to clean-up the receivers list in Mailman, that is Mailman removes all To/CC addresses which are members of the list?
One of the annoying things using Reply-To munging in open lists is, that you cannot easily include external authors in replies, whether you are using reply-to or reply-to-all in your MUA. It would be nice, if the sender could be added to the Reply-To addresses in the case, that the sender is not a member of the list, so that replies automatically go to the list AND the author. (Of course, this should be done only, if the sender didn't set his own Reply-To header already.)
As an variation to the proposal 2) it also would be nice to have the sender in general be added to the Reply-To header. That would make replies behave similar as the reply-to-all in case of no Reply-To munging. This makes it easier to reply only to the author, and not the whole list, by just deleting the list address while replying. Because you can also have address accumulation in that case, if users use the reply-to-all function, you could combine this option with the "receiver clean-up" option from proposal 1).
As proposal 3) doesn't need to know the member status of addresses, you can also easily implement it in the MTA, therefore it is the least important one.
What do you think about that? (With some help I can also try to implement this on my own, if there are chances to include it into the official Mailman.)