nmh (new MH) is a powerful electronic mail handling system. It was
originally based on version 6.8.3 of the MH message system developed by
the RAND Corporation and the University of California. It is intended
to be a (mostly) compatible drop-in replacement for MH.

nmh consists of a collection of fairly simple single-purpose programs
to send, receive, save, retrieve, and manipulate e-mail messages.
Because nmh is a suite rather than a single monolithic program, you may
freely intersperse nmh commands with other commands at your shell
prompt or write custom scripts that use these commands in flexible
ways.