Subject tag [Dovecot] is gone

I've actually been thinking about it almost since the beginning. It's just been annoying waste of space on my screen. And more importantly nowadays it's also breaking DKIM/DMARC signatures. So if somebody still uses Subject-based filtering it's about time to switch to List-ID header based filtering now.

Another thing I'm wondering about is if I should allow text/html parts, because removing them will also break the DKIM signatures. Or mainly I'd like to allow only multipart/alternative with text/plain + text/html, but I don't think I can configure Mailman to support that.