I tried the ISINTEG as suggested above, but this did not work for my specific situation. After moving almost 600 mailboxes from this store, I had two mailboxes that would not move. Since it was just two users I even tried a defragmentation using ESEUTIL, but that had no affect.
I then attempted to move the mailboxes once more from ESM. After it failed, I actually checked the little box to view the optional .xml error report instead of looking in the Application log for the failure alert. In this report, each mailbox actually showed that there was a corrupt, or at least an unreadable email. It even detailed the sender information. With this information, I was easily able to find the problematic emails in their respective mailboxes. Both of the offending emails had attachments that with non-standard formats. I was able to make a copy of one of the emails, but had to delete the other. The only folder it would let me move it to, was the deleted items folder. Then, I could delete the email. After deleting the emails, the mailboxes moved just fine.
for a hotfix applicable to Microsoft Exchange Server 2003.
This problem may occur if the store to which you want to move the mailbox contains a size restriction. See ME924174
to solve this problem.
I have seen this error after moving mailboxes from Exchange 2000 SP3 to Exchange 2003 SP1. Dismount the mailbox store, open a command prompt, go to \exchsrvr\bin and run “isinteg -s servername -tests alltests –fix”. Keep running isinteg until no errors or warnings are found. Afterwards mount the store again and the error will be gone.