Check Email Delivery is a plugin for Nagios that allows you to
check functionality within your email environment.

Some typical uses of this plugin include:
* check SMTP server
* check IMAP server
* check email delivery loop
* check auto-responder function
* keep an eye on email lag
* monitor automated mailboxes
* aggregate check results of multiple plugins
* check email-to-FTP or other special email gateways

WWW: http://buhacoff.net/software/check_email_delivery/