We have had a few employees leave our company over that six months. What I typically do is change their password, remove them from all their email groups, and disable their user account in active directory. I don't completely delete their user account for quite awhile, in case we need to re-enable their account and check something in their exchange mailbox, etc.
So, we had a need to check one of the users mailboxes for some previous emails, and I enabled their account, and even reset their password, just to make sure I knew what it was and there was no question about the password. I tried to log onto OWA as this user, but it would never log in and kept failing. I ended up adding their user account to my computer and logged in as them, which worked, but then when I went to configure Outlook, it "checked the name" just fine, but it kept prompting me for user credentials.
I have verified over and over that the password is correct, but I am wondering if because the user account was disabled for so long in Active directory, that maybe something happened to the mailbox on exchange?
We have a simple setup with a single W2K3 Standard server runing Active directory, and a single Exchange 2003 server.