Exchange question

[daveshel]

I am migrating a local government department of 150 users from GroupWise to Exchange 2003. I need my users to have access to 5000 users in other departments, none of which are in the same forest as my department. I am looking for a solution like the Exchange 5.5 directory import/export that will allow access to these addresses without having to add 5000 contacts to my AD.

Thanks.