When querying the Message Queues page of the Control Center web interface, some messages are queued in the Inbound queue with the error: 421 4.7.7 [internal] Unable to process message at this time.
Querying the message queues from the command line via the mta-control command to query queue also shows the same issue. On further review of the mail log, there are errors stating “Deferring message: failed to filter message” .
This error message can be caused by a number of underlying conditions which are preventing the Brightmail Engine from scanning messages including
The most direct means of resolving this issue is to reboot the appliance or virtual machine as this will free all allocated resources and restart all services.
If this fails to resolve the issue, please review the logs for the following services for errors: