make config does not show the option for building mutt with mail/mixmaster support.
Can you submit a patch? That would be very helpful.
This is fixed among other things by https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=203056
A commit references this bug: Author: riggs Date: Sun Sep 13 09:18:11 UTC 2015 New revision: 396802 URL: https://svnweb.freebsd.org/changeset/ports/396802 Log: Update to upstream version 1.5.24, add MIXMASTER OPTION PR: 203056, 202114 Submitted by: Udo.Schweigert@siemens.com (maintainer) Changes: head/mail/mutt/Makefile head/mail/mutt/distinfo head/mail/mutt/files/extra-patch-sidebar head/mail/mutt/files/extra-patch-sidebar-nntp head/mail/mutt/files/extra-patch-trash-purge head/mail/mutt/files/patch-CVE-2014-9116 head/mail/mutt/files/patch-Makefile.am head/mail/mutt/files/patch-curs_lib.c head/mail/mutt/files/patch-examples head/mail/mutt/files/patch-gpg_agent_info head/mail/mutt/files/patch-mktemp head/mail/mutt/files/patch-pgpkey.c head/mail/mutt/files/patch-smime-self head/mail/mutt/files/patch-smime-sender head/mail/mutt/files/patch-staging-Makefile.am