1. mail delivery agent with filtering abilities maildrop is a replacement for your local mail delivery agent. maildrop reads a mail message from standard input, then delivers the message to your mailbox. maildrop knows how to deliver mail to mbox-style mailboxes, and maildirs (a mail storing format introduced by Qmail). maildrop can optionally read instructions from a file on how to filter incoming mail, and, based upon the instructions, deliver mail to alternate mailboxes, or forward it to somewhere else, like procmail. Unlike procmail, maildrop uses a structured filtering language that's a bit easier on the eyes. From Debian 3.0r0 APT