Automation Centre (Popularity: )
http://www.acentre.com Automation Center provides users of Microsoft Outlook and Exchange server with solutions for project management, time and billing, expense tracking ...
BrightWork (Popularity: )
http://www.brightwork.com Product Management, Software Development and Program Management applications built on top of Microsoft Exchange.
MessageOne (Popularity: )
http://www.mspt.com Providing a way to immediately measure, manage, and get critical insight into global enterprise email systems.