Viewing Exchange 5.5 GAL from Exchange 2000

Romain mailed me with his exchange problem.  We’d been chatting at one of my technet evenings – I’d been talking about blogging – not Exchange incidentally, and I’d mentioned that Exchange was my favourite Microsoft product (in conjunction with Outlook of course – what’s yours by the way?)

He had the following problem. The company, He works for for is running Exchange 2000, while the group which has acquired the company, is running Exchange 5.5.  While they are likely to have to upgrade soon, they have no information as to when this is going to happen.

The key problem people are complaining about is the inability to view other members of the group emails and reciprocally for them to find email addresses. The ability to schedule meetings and other exchange features are not viewed as critical until they upgrade.
1) In the interim, is there a way to keep both global address lists updated, say every fortnight, with the other group emails?  What would be the most elegant solutions? Any gotchas we should know about.
2) Alternatively is there a path for us to go back to Exchange 5.5, here again only migrate the emails, until we all upgrade to 2003.
3) Any other comments welcome.

Sounds like a job for the Active Directory Connector.  I’ve blogged about this a few times recently, recorded a blogcast on how this is configured, and talked about how to configure the 2 way connection agreement.  Here’s how to configure the ADC by the way.