There can be many different reasons why an administrator would want to migrate from Microsoft to Linux, whether it be to reduce cost, improve server efficiency or simply because the administrator is more proficient in Linux. One of the main difficulties you will always come across is finding a suitable solution that will be able to replace the Microsoft counterpart, especially if you are dealing with an Exchange environment. In the past you would have had to install an array of applications and servers just to be able to provide all the features that Microsoft Exchange has to offer.