I moved this user mailbox from one datastore to another on the same mailbox server. The move showed completed successfully but I am getting the following in Event viewer - Application log every minute. Exchange 2010, Windows 2008 R2, Event ID 10001.
Mailbox cleanup could not completely remove the mailbox for user /o=First Organization/ou=Exchange Administrative Group (FYDIBOHF23SPDLT)/cn=Recipients/cn=jsmith(Root Fid 1-136918B5) following mailbox removal. Encountered error 0xfffffae8. Should this message continue to persist for the same mailbox, it may be indicative of a problem that requires further investigation.