I received word that my posts to epel-devel@lists.fedoraproject.org were getting marked as spam by gmail. I looked at the headers and the problem was arc=fail (body hash mismatch) in the Authentication-Results header. It only happens on email senders that generate an ARC hash, as my email provider does. According to mailman news this was fixed in version 3.3.6:

ARC signing now signs after the message has been personalized and decorated. (Closes #896)

but according to the X-Mailman-Version header received, lists.fedoraproject.org is using version 3.1.1. Here is mailman issue #896.

I expect this will likely be blocked by #8455.