>So I got a user report that exmh was doing something weird with bcc:. >[...]
Geez, Valdis, people have only talked about (n)mh's weird bcc for ... 30 years? :-) Even in threads you have commented on, as recently as a year ago: https://lists.nongnu.org/archive/html/nmh-workers/2019-02/msg00004.html I replied to that message on exmh-users, giving the history of things and some possible solutions. --Ken