Scope:
This solution applies to all Barracuda Spam Firewalls, firmware versions 3.5.10.029 and above.
Answer:
There are two reasons that this may occur:
- It could be that there is a mail relay in front of the Barracuda Spam Firewall, and since all email is seen as originating from a single source, the Barracuda Spam Firewall's Rate Control feature is being triggered. If this is the case, you should exempt your mail relay from Rate Control and other IP-level checks.
- In Firmware version 3.5.10.029:
Specify it as a Trusted Forwarder on the Basic > IP Configuration page. You can also exempt IP addresses from Rate Control specifically on the Advanced > Rate Control page. - As of Firmware 4.1.2.007:
Specify it as a Trusted Forwarder on the Basic > IP Configuration page. You can also exempt IP addresses from Rate Control specifically on the Block/Accept > Rate Control page. - The Rate Control may be set to a low value. You can check this number on the Advanced > Rate Control page. If it is too low you should adjust the value accordingly; the recommended Maximum Connections Per Client / 30 Minutes value is 50.
https://campus.barracuda.com/solution/50160000000GRxaAAG