Some messages with the Action "Hold in Spam Quarantine" instead accumulate in the Messaging Gateway (SMG) delivery queue and never appear in the Spam Quarantine.

Mar 18 2013 19:44:55 [SmtpWorker-12] ERROR - Cannot create a spam message in the database. 
com.symantec.smg.controlcenter.internal.dataaccess.DataAccessException: An
unexpected database error has occurred. Please contact your system
administrator. ; nested exception is: 
	 com.mysql.jdbc.exceptions.MySQLIntegrityConstraintViolationException: Column
'from_addr_email' cannot be null

Messages with a malformed "From:" header which do not contain a properly formatted email address are not accepted by the SMG Spam Quarantine. These messages are held in the delivery queue until they are eventually bounced.

This is a known issue with SMG 10.6.3 and earlier.

These messages cannot be accepted by the Spam Quarantine but can be routed to another mail server via the command line 'mta-control' command. Please see Rerouting messages in the delivery queue for more information.

This issue has been addressed with the SMG 10.6.4 release.