Mail command with mailx extensions.

    Mailx command is based on BSD mail command, but it also provides some
enhanced features such as:

o Edit header information.
o Use pager program to display long message.
o Add pipe (|) command.  You can pass the mail message to the shell command by
  using this feature.
o Add Save, Copy command.
o Add askcc, askbcc command.  The mailx program ask you Cc: and Bcc: at the
  beggining.
o Add hsubject command.  This is similar to subject command, but it only
  displays Subject: headers.
o Add tilda escape command.

See also the files in ${PREFIX}/share/doc/mailx directory.