Ron Guerin writes:

With great sadness, I'm trying to deal with the DMARC problem certain providers have decided to create for everyone else, and for some reason, even after turning the mung option on in the web interface, there's no munging going on. (wrap doesn't wrap either)

I have ALLOW_FROM_IS_LIST = Yes in mm_cfg.py . I have restarted Mailman.

Debian has a habit of moving configuration files around. On my Debian system:

-rw-r--r-- 1 root root 4629 Apr 16 05:15 /etc/mailman/mm_cfg.py lrwxrwxrwx 1 root root 22 Feb 3 22:33 /usr/lib/mailman/Mailman/mm_cfg.py -> /etc/mailman/mm_cfg.py

Figure out where your mm_cfg.py file or files are, make sure that the one you're editing is the one that actually controls Mailman.