We have been struggling with this for about 2 years now.
Here is some information from my experience.

Our NT admins bought some auspex NAS servers (NS2k)
and told us about it after the fact.  Luckily, they
only used the NFS portion of the box. Until 2 months ago.
We have been NFS mounting to another "supported" server, then backing
up the data with DOMAIN statements in the dsm.opt.
The problem with this (which is affecting us now) is that
we only back up the the unix file permissions, and can't
get the NT ACLs.  without an NDMP supported client,
its one or the other, but not both.  This may not
be an issue with email delivery though.
We felt this was better than installing the old auspex
client on the server, just so NAS can do what it was made for,
servring files and not running some weird application

As to NDMP support in TSM.  I have talked to the Develepors
a number of times about this, and they promised me an NDMP
client by the middle of first quarter this year. Last I heard
it was middle of second quarter.  From what I can tell the
only benefit of NDMP has over NFS mounting/backing up
is that you can get both sets of ACLs.

shawn


___________________________________________________________
Shawn M. Drew
shawndo AT tivoli DOT com
ADSM/TSM Systems Administrator