I have a working implementation of Chatmail on FreeBSD now.
https://github.com/feld/chatmail-cookbook
I wonder if
Note: it adds a custom package repo to fetch a couple things not in the ports tree right now (incl a Dovecot patch I need to see if we can get into the port or as a flavor). It's hosted on my home fiber internet, but it might be slow. I'm going to get it moved somewhere with better bandwidth soon.
edit: also the FreeBSD 14 package set is still building... 15 is ready though