Can someone post the code (in it's entirety) to determine the Exchange
server that the current logged on user belongs on?

I've tried all the CDO code snippets on the web (which are all the
same), but whenever I run it I always get the same error:

[Collaboration Data Objects - [E_INVALIDARG(80070057)]]

I'm running this on Outlook 2003 (yes I have CDO installed) from an
Outlook form. Our backend is Exchange 2003 SP1.

The actual code it always chokes on is:

strHomeServer =
objSession.GetAddressEntry(strUserID).Fields(PR_EM S_AB_HOME_MTA)

Yes, I've also tried adding in the hex code directly (&H8007001E).

Yes, I did the session logon first. Although when I first ran it just
using the code snippet I found it worked! And the code never defined
what objSession was. Since then I did some changes and now I can't get
it to work.

I just don't get it.