We have a 5.5 exchange with 2003 server. Since installing another 2003 server R2 but now we cannot create mailboxes on either 2003 server or at least they don't show up in Exchange manager. Actually, I can't say that because the 5.5 and 2003 server connector got screwed up last week and I reconfigured it a couple of days ago. So that is one change and the other change is the new 2003 R2 server which is on a seperate IP over a WAN with another DC but is the same domain.
On the 5.5 side we can create mailboxes and create new users. There is an AD Connector on the original 2003 server that points to 5.5 so I assum it is working if I can create a new user from 5.5 mail server and an AD account.
I am wondering if I have to update the Exchange forest prep/domain prep with the R2 version to get things going?
UPDATE: I have the user on the new 2003 server successfully get into the mailbox where as before he could not. His mailbox was previously on 5.5 and was moved. However, when sending mail to him we get an error from the 5.5 saying undeliverable as if 5.5 thinks his mailbox is still there or doesn't know about the new server? But there is a connector between 5.5 and the other 2003 server.