When email to a specific domain or route is in the Delivery queue and an attempt is made to re-route all messages to that route, to another MTA, from the Messaging Gateway (SMG) Control Center, this error may be displayed: "Error re-routing messages from the message queue. Please check the Control Center log for details", when the "Use MX Lookup for non-local mail" setting is configured under the "Outbound Non-Local Mail Delivery".

"Error re-routing messages from the message queue. Please check the Control Center log for details."

SMG will not re-route messages when set to use MX lookup to determine the route.

The recommended resolution to re-route the messages is:

1. Update the MX records associated with the domain to contain an accessible list of mail servers
2. Go to Administration > Configuration > scanner > DNS/Time
3. Click Flush to flush the DNS cache.
4. Flush the delivery queue Status > Message Queues.
5. Click Display Filtered 
6. Click Flush All

The alternative is:

1. Under Administration > Configuration > scanner > SMTP > Outbound
2. Change the "Outbound Non-Local Mail Delivery" from "Use MX Lookup for non-local mail" to "Relay non-local mail to" and configure an IP that is not a mail server. (NOTE: This will prevent any email in the queue from being delivered to an invalid host and being rejected)
3. Re-route your messages to another MTA host.