mailx - A tool to check the email box.

Mailx is derived from Berkeley Mail and is intended provide the
functionality of the POSIX mailx command with additional support
for MIME, IMAP, POP3, SMTP, and S/MIME. It provides enhanced
features for interactive use, such as caching and disconnected
operation for IMAP, message threading, scoring, and filtering.
It is also usable as a mail batch language, both for sending
and receiving mail.