We switched from spam filtering software installed on our internal Exchange server to Barracuda Essentials Advanced Email Security (cloud based) solution. To get everything working the way I want it, I need to make two changes to my SonicWALL NS 2600. Unfortunately, I'm not strong with that device, so I'm hoping for some guidance in setting it up correctly.
Task 1 - Allow Barracuda to do LDAP lookup so spam to non-existent email addresses is automatically blocked.
If I understand this correctly, I need to set up a NAT for this, allowing traffic from Barracuda's IP address(es) to reach my domain controller over LDAP (port 389.) I think I need to set up two Address Objects (public and private) and then use those in a NAT policy. Problem is, I tried this and must have done it wrong. When putting the public IP into the Barracuda Cloud Control console and testing the connection, I got an "unable to connect to (IP)" error.
Task 2 - Block all incoming traffic on port 25 unless it's coming from Barracuda.
I'm getting spam that isn't passing through the Barracuda filters. Barracuda support suggests blocking all email (port 25) unless it's coming from their IP address(es). On the SonicWALL, I'm not even sure where to find or make these settings.