Allan Streib <astreib@indiana.edu> writes: > Notmuch/0.20.2 (http://notmuchmail.org) Emacs/24.4.1 > > Replying to a message in a deeply nested thread can trigger a complaint: > > sendmail: command failed: 550 5.7.1 Delivery not authorized, message refused: Message is not RFC 2822 compliant > > The problem is a References header that is too long/not wrapped. > > Regards, > This bug should now be fixed in notmuch (commit 95e9c137e18a, will be part of notmuch 0.24) d