I have installed exchange 2007, and need to expose the M Drive for message store. In Exchange 2003, all I needed to do was create a string value in the registry key for Exchange. That key is non existent for 2007. All help is greatly appreciated, and urgently required. Thanks Jeff

M drive for message store (Exchange Installable File System (ExIFS)) is a Discontinued Features of Exchange 2007 so thats the reason you are not able to map M drive. http://technet.microsoft.com/en-us/library/aa998911.aspx http://exchangeshare.wordpress.com/2007/04/15/de-emphasized-discontinued-features-in-exchange-2007/