S-nail provides a simple and friendly environment for sending
and receiving mail. It is intended to provide the functionality
of the POSIX mailx(1) command, but is MIME capable and optionally offers
extensions for line editing, S/MIME, SMTP and POP3, among others.
S-nail divides incoming mail into its constituent messages and allows
the user to deal with them in any order. It offers many commands
and internal variables for manipulating messages and sending mail.
It provides the user simple editing capabilities to ease the composition
of outgoing messages, and increasingly powerful and reliable
non-interactive scripting capabilities.