We are using 2003. I have checked the settings of both accounts against others and can find no discernable differences. I will look again.
As regards using a pst import, I would prefer to stick with the wizard if possible based on your answer to another post of mine (
here).
Previous attempts to export mailboxes to pst files from exchange using exmerge were not successful. Unfortunately, we no longer have an exchange "specialist".
By the way, I had to mirgrate the mailboxes using the migration wizard one at a time (it failed otherwise). Carrying out the operation on a per mailbox basis resulted in no errors at all (except for the two accounts).
Paul