mailutils

About mailutils

From Debian's package description

GNU Mailutils is a rich and powerful protocol-independent mail framework. It contains a series of useful mail libraries, clients, and servers.

This package contains the GNU mailutils versions of dotlock, frm, from, mail, messages, mimeview, movemail, readmsg and sieve. They are capable of speaking POP3, IMAP, mbox, MH, Maildir and dotmail.

dotlock -- lock mail spool files. frm -- display From: lines. from -- display from and subject. mail -- the standard /bin/mail interface, mail sender and reader. messages -- count the number of messages in a mailbox. mimeview -- display files, using mailcap mechanism. movemail -- move messages across mailboxes. readmsg -- extract selected messages from a mailbox. sieve -- a mail filtering tool.

From Debian's description of the mailutils package, under that package's license.