Moved Mailbox and OWA Problem loggin into the wrong mailbox exchange 2003

We have had a user mailbox become corrupted that would no longer accept mail, The mail queued in the local queue and never got delivered. After much googling the only fix seemed to be export the mail to pst and disconnect the mailbox from the user, then create a new mailbox for that user and import the mail in.

This I was able to do succesfully email is now flowing again and all the mail is available. However as a precaution I reattached the old mailbox to a new user account called "userbackup" so the mail wouldnt be deleted by the server just incase the PST backup wasnt complete etc.

The problem is now if i login to webmail with the origional users credentials it logs him in to the origional corrupt mailbox which is attached to a different users Active Directory Account, and i cant seem to access the new mailbox from webmail.

This is mainly a problem because now his active sync phone cant access the new mailbox and new mail.

Does anyone have any ideas why this might be and how I can get webmail to point to the correct account?

thanks