Email Client for the Terminal?
Specifically for OpenBSD mailing lists. Is it possible to use just mail(1) for it? I want to use just what is in base. If everything fails... Oh well, besides mutt, any other good email client, if possible simpler?
(Other software has bugs. Mutt has fleas.)
See also: Neomutt.
Alpine. Probably fits your requirement for "simpler", though mutt, as with vim, strongly rewards familiarity.
Gnus or mu4e, under Emacs.
Old school: Elm, pine.
See: <https://en.wikipedia.org/wiki/Text-based_email_client>.