Centaur - the immediate email notification.

Latest release - centaur-0.1.tar.gz. Changelog and README.

This program is intended to IMMEDIATELY notify an user when its mail arrives. To do so IMAP IDLE command is used. Thus, if you have no IMAP account, or your IMAP server does not support IDLE, you're out of luck.

Basic ideology after Centaur is described in this article.