MESDP allows you to import users from the Active Directory.

It offers the feature to import at either forest or OU levels.

A future development I would like to see is the ability to import users based on security groups - no I don't want to use LDAP/s

E.g. All my users are a member of a specific security group called XYZ and the group only contains active users. As such, if I could use that group to import users, it would always keep my SDP contacts list up to date.