Create Custom IP Policies
Once the true sender of an email message is identified, the reputation and intent of that sender should be determined before accepting the message as valid, or "not spam". The best way to address both issues is to know the IP addresses of trusted email senders and forwarders and define those as exempt from scanning by adding them to a list of known good senders.
Add exempt/trusted sender IP addresses and block those you know are not trusted on the Inbound Settings > IP Address Policies page.
You can create a list of Trusted Forwarders by specifying one or more IP addresses of machines that you have set up to forward email to the Barracuda Email Security Service from outside sources. The Barracuda Email Security Service exempts any IP address in this list from Rate Control, Sender Policy Framework (SPF) checks, and IP Reputation. In the Received headers, the Barracuda Email Security Service continues looking beyond a Trusted Forwarder IP address until it encounters the first non-trusted IP address. At this point, Rate Control, SPF checks, and IP Reputation checks are applied. Configure on the Inbound Settings > IP Address Policies page.