By-default, Exchange Server 2000 supports mapping Installable File system to drive M. But Exchange Server 2003 does not support this mapping. This drive mapping is required when you use Microsoft Front Page Extension and the Microsoft Web Storage System. Microsoft recommends only use this feature if specific reason to do so.

Here are the steps to enable M drive in Exchange Server 2003:-

1.       Click Start, and then click Run.

2.       Type regedit, and then click OK.

3.       Open the registry by using regedit command:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\EXIFS\Parameters

4.       On the Edit menu, point to New, and then click String Value.

5.       Type DriveLetter, and then press ENTER.

6.       On the Edit menu, click Modify.

7.       In the Value data box, type M, and then click OK.

Note If you want to map IFS to a drive letter other than M, type the drive letter that you want in the Value data box.

8.       Quit Registry Editor.

9.       Restart the Exchange Information Store service.

For more detail, click here.

Exchange Server 2003 SP2 Features:

• IMF (Internet Messaging Filter)
• New for mobility is direct push, which is an Exchange technology that maintains an open connection between the mobile device and the server. Remote wipe is another new feature, and it enables administrators to delete sensitive data from a lost or stolen mobile device.
• support for certificate-based authentication, use of S/MIME to sign and encrypt mail, and server-based synchronization of Tasks.
• Sender ID
• For Exchange Server 2003 Standard Edition, the hard-coded licensing database size limit has been increased from 16 GB to 75 GB. The administrator can set a protective database size limit (prevent unintentional database size growth). The default value will be 18 GB in SP2 for Standard Edition and the default can be changed.
• Public folders are now more manageable. Administrators can now track who deleted public folders, stop and resume public folder replication, synchronize the public folder hierarchy, propagate access control list (ACL) changes through public folder hierarchy, and propagate replica list changes through the public hierarchy.
• There is a new version of the offline address book (OAB 4.0) that features the reduction in the OAB size, differential OAB update files, indexing based on locale setting, and improved diagnostic logging.

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