I've been running my mailing list for a few years with "Munge From" to
defend against DMARC rejection. This means that my messages get
From: Joe User <mymailinglist(a)mydomain.com>
Reply-To: Joe User <joe(a)example.com>
That mostly works, but sometimes confuses people a bit, and just now
I've had somebody send what I think was intended as a private address to
that From line, not to the Reply-To line. (I think their e-mail client,
Pegasus, has an excessively flexible policy on which headers to use for
a reply and may be subtly misconfigured, but maybe they just naively
copied the From line.)
That's leading me to wonder whether there's another way, whether I can
leave From alone and still get past the DMARC checks. Wikipedia tells
me that DMARC passes if either SPF *or* DKIM passes. There's no hope
for SPF with the original sender in From, because the mailing list
server isn't the user's mail server. However, DKIM seems like it
*might* pass, if I'm careful in how I configure the mailing list. In
particular, it looks like I'd have to get rid of the message footer.
That would be OK. Looks like I might also have to kill off the
[ListName] addition to the Subject, which is less OK but might be better
than the alternative.
Before I go recruit a couple of users from several DMARC-using providers
and run some tests, can anybody tell me if there is any hope there, and
maybe share some configuration tips?