No message loaded

Following error is reported in the appliance livelog:
Archive Process spooler entry error: An exception was raised on the server: AddMailTransactionFile Exception: [/mnt/storage/CIFS/{.....}/...../reddoxx.rdxacs] - No message loaded.

The mail that is to be archived is broken.
The respective mail needs to be deleted from the Archive Spooler (Admin Webinterface -> MailDepot -> Archive Spooler)
The ID of the mail which needs to be deleted can be seen in the error message.