You might be interested in knowing about a very cost-effective and easy-to-manage Linux and Open Source based email & collaboration product for companies. Check - http://www.synovel.com/collab/ It has a web based administration panel for managing servers and users along with desktop client and web access.

Microsoft has its own cost effective and easy to manage product which provide all features of Exchange as a cloud computing, Microsoft Online Services... http://www.microsoft.com/online/default.mspxAmit Tank | MVP Exchange Server | MCITP: EMA | MCSA: M | http://ExchangeShare.WordPress.com