SMTP Queue full
If users are receiving rejection messages from the mail server with the message Diagnostic-Code: smtp;connection with mx.vwave.net is broken it is possible that the outbound SMTP queue is clogged with spam.
Identify the offending user
In order to clear out the queue and not affect legitimate email traffic, the spam sender must be identified. This can be done by checking the queue in Communigate, under Monitors > Mail > Queue, and selecting some of the messages to see the sender and recipient, or if there is an external spam firewall, such as a Barracuda Email Security Gateway, checking the outbound message log there.
Halting the spam
Once the offending user has been identified, disable their account in Communigate.
Clearing the queue
Now that we have stopped mail from being sent, we need to do something about the clogged queue. Log on to the Communigate server via SSH and navigate to /var/CommuniGate.
The script for emergency cleaning CommuniGate queue. You may need this tool badly if your queue is flooded with spam or bounces and you want to clean it quickly without stopping the server.