Question : Outlook can not verify valid mailbox

We are running E2007 and everything has been fine for a couple of years now.

But for some reason now when I go to a computer that has Outlook 2007, enter valid mailbox and click Check Name I encounter the error message noted in the attached screen shot. This occurs on workstations that are on the internal LAN (small office...only about 20 computers)

I can ping the mail server by name and IP. And I can browse to it via UNC pathing.

Any ideas?

Attachments:

validate-account-error.JPG (95 KB) (File Type Details) 

error message

Answer : Outlook can not verify valid mailbox

I think I noticed something interesting. The MS System Attendant is not started on the Exchange box. I started it and now Outlook seems ok. Still testing. Stand by.