This solution applies to all Barracuda Spam Firewalls.
These messages are almost always the result of a spammer attempting to utilize the device as an open relay. This occurs due to the requirement of listening on Port 25 to receive SMTP transmissions. We have no control over what requests come into the Barracuda appliance but we do have control over whether or not we allow it.
If you are receiving several attempts to send outbound mail through the Barracuda appliance from external IP addresses but they are being blocked, the Barracuda Spam Firewall is successfully stopping attempts to utilize it as an open relay and there is no reason to be concerned.
In the event that some, or all, of those messages are allowed, it may indicate a misconfiguration on the Barracuda Spam Firewall. Please contact technical support immediately if this is the case.
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