Messages with the "Deliver to Spam Quarantine" action are not appearing in the Spam Quarantine but instead remain queued in the Messaging Gateway delivery queue with a "421 Closing Connection" message as the last error.
"421 Closing Connection"
Mar 18 2013 19:44:55 [SmtpWorker-12] ERROR - Cannot create a spam message in the database.
unexpected database error has occurred. Please contact your system
administrator. ; nested exception is:
Column 'from_addr_email' cannot be null
This is caused by a malformed From header in the message which is preventing the message from being inserted into the Spam Quarantine database.
This is addressed with the SMG 10.5 release.