There is no support for SME over NFS. For SMSQL there is support with this when running SnapDrive 6.3.1 and SnapManager SQL 5.1. I don't remember the exact reason for SQL and not Exchange but it was something to do with VSS differences and why it isn't supported for SME yet.
You should be able to use iSCSI initiator. IF you even have iscsi software initiator you can open microsoft iscsi initiator from start menu, add your filer to portal address, connect or login in the initiator. From SDW under initiators it will show up this initiator. You should be able to use that to create LUN. (Did you try this?)
So, I just used the iSCSI initiator and was able to create a LUN and add it to the host (prooving that the iSCSI initator does work), however, I am not able to manage this LUN using SnapDrive.
When I open SnapDrive and try to connect to the LUN I have already created I get to the point where it asks for the initiator, and the iSCSI initiator is not shown on there. it only shows a FC initiator (which is not active/setup/configured) and I am unable to select/use it.
So I guess my next question is how to I make the iSCSI initiator (which I have verified is working) show up in SnapDrive?