Nail

Nail is a mail user agent derived from Berkeley Mail. It provides the functionality of the System V and POSIX mailx commands.

Additional features include support for MIME, IMAP (including caching and disconnected use), POP3, SMTP, S/MIME, international character sets, maildir folders, message threading, powerful search methods, scoring, and a Bayesian junk mail filter.

Nail can be used as a mail batch language in nearly the same way as it is used interactively. It can thus act as a mailbox filter, can fetch mail from remote accounts, and can send files as attachments.

Here are some key features of "Nail":