maildrop

The mail filter/mail delivery agent from the Courier Mail suite

maildrop is a replacement for a local mail delivery agent. maildrop reads a mail message from standard input, then delivers the message to an mailbox. maildrop knows how to deliver mail to mbox-style mailboxes and maildirs. "maildir" is a mailbox format used by Courier, Qmail and Postfix. maildrop optionally reads instructions from a file, which describe how to filter incoming mail. These instructions can direct maildrop to deliver the message to an alternate mailbox, or forward it somewhere else. Unlike procmail, maildrop uses a structured filtering language. maildrop is written in C++, and is significantly larger than procmail. However, much more efficiently. Unlike procmail, it uses resources better and will not read a 10 megabyte mail message into memory, but save large messages in a temporary file, and then get filtered. If the standard input to maildrop is a file, and not a pipe, a temporary file will not be necessary. maildrop checks the mail delivery instruction syntax from the filter file before attempting to deliver a message. Unlike procmail, if the filter file contains syntax errors, maildrop terminates without delivering the message. The user can fix the typo without causing any mail to be lost.