I am going to "disable" an existing user mailbox in Exch 2010 and create a new mailbox with the same username. When I did this last time, I noticed two problems:
(1) After importing PST into the new mailbox, the user complained about suggested contacts would not come up as he creates a new email and enter the email address. So I like to know how to export and import Suggested Contacts. Even if Suggested contacts did exist in his C drive, when you create a new outlook profile, the new account did not recognize existing Suggested Contacts associated with old mailbox. NK2 was much simpler.
(2) After I created new mailbox and imported PST into the account, people (on the same network) would get "undeliverable" emails when sending emails to this new mailbox even if username was the same. I learned later that I needed to add X.500 email address to the account instead of waiting for global address book is downloaded into each user's OUTLOOK.