Hello,
This error may be caused due to the foll reasons:
1) Anti-virus software accessing the Information Store at the same time as the backup, i.e. using the same Messaging API as Backup Exec does.(It is then recommended to stop Anti-virus software services when backing up the mailboxes).
(2) Multiple levels of embedded mail messages (a message attached to a message attached to a message etc.)(remove message)
(3) Automated system messages (undeliverable, over size limit etc.)(remove message).
(4) The message / attachment is really corrupt (can't open, view or execute)(remove message).
(5) Virus infected Information store (clean for virus).
(6) Very long subject lines (remove message).
(7) Very long attachment names (remove message).
(8) Very large attachments (might give out of resource like errors)(remove message).
Thanks,
NOTE : If we do not receive your reply within two business days, this post would be marked assumed answered and would be moved to answered questions pool.