Hi Per,
AFAICT, mailman offers only two (marginally useful) options, per list - replace from with list address or wrap message in an outer message. Neither is of much use to us, we don't want the From: address to change.
you realize, though, that it's impossible to keep "From:" as-is if you want to deliver postings reliably to all recipients? If you keep the original "From:", then those the postings will potentially fail the SPF check. I have that exact problem with my private domain cryp.to. I cannot post as simons@cryp.to to mailing lists that don't re-write "From:" because sites like gmail.com will reject those messages. When I found out about that, I could not believe that they would check the SPF records against the "From:" header found in the message payload, but, well, they do. The only solution for me was to introduce a sub-domain nospf.cryp.to that doesn't have SPF records at all, and then I can use that domain to post to lists that don't re-write "From:".
What would you expect Mailmain to do that it doesn't?
Well, optimally we would want to keep our [LISTNAME] Subject prefix and our helpful footer :-)
You can! All you have to do is to make sure that your mail server creates a proper DMARC signature and rewrites the "From:" header for those addresses that have SPF records defined. That's exactly how I run my lists in mailman and it works fine. Best regards, Peter