Slugmail 
An email based reminder service.
http://www.slugmail.comMailTester.com
Online tool to test an e-mail address. Find out if is valid, why it bounces or what type of mailserver the mailbox is on.
http://mailtester.com/
Postini
In-line infrastructure for pre-processing email messages in real time. Allows email management applications to be integrated into any SMTP email system.
http://www.postini.com/
