Cc'ing balug-admin.
Quoting Michael Paoli (Michael.Paoli@cal.berkeley.edu):
I did also try some testing ... posted from @gmail.com, @yahoo.com, and at least two different ways from another ISP ... and I didn't spot any issues posting (used BALUG-Test for such tests). And, I think both Gmail and Yahoo! are relatively heavy on the use of SPF and DKIM (and/or DMARC?)
To clarify, DMARC is an omnibus package, invented by Yahoo, of anti-forgery technologies that incorporates Yahoo's DKIM (DomainKey Identified Mail, a successor to Yahoo's DomainKeys) and Meng Wong's SPF.
Mailing list manager (MLM) package have no problem with SPF because they supply an entirely fresh SMTP envelope on the retransmission to subscribers. In this, they differ from cross-system /etc/aliases and ~/.forward entries, which do _not_ supply a new envelope.
MLM packages have big problems with Yahoo's standards (the DKIM portion of DMARC, and legacy DomainKeys) because MLM's modifications to posting text and headers upon retranmission to subscribers have a strong tendency to break DKIM's (and DomainKeys's) cryptographic attestation about the integrity of the text and headers.
The specific Mailman munging kludge I recommended addresses this problem by dumbing down Mailman's treatment of the internal 'From: ' header where necessary to avoid breaking DKIM (/DomainKeys) attestation. The cost of this is grievous, substitution of the mailing list's originating address for the user's, but this is the least amount of damage that appears able to make Mailman cope with what IMO is a really crappy and MLM-hostile antiforgery design.
I _really_ detest DKIM and DMARC, and think Yahoo, Inc. botched them, but detesting them doesn't make them go away. And naturally yahoo.com is the worst offender in deploying an aggressive DMARC policy, with GMail not far behind.
OTOH, if you say your test mailings from those domains worked, good. I hope that continues.