Not receiving emails from O365/Outlook.com companies with Barracuda email security

Hello,

We did get a solution.  Our situation involved incoming mail from several O365 clients hosted on barracuda network servers, coming to our Exchange server that is behind our SonicWall Firewall and using the SonicWall anti-spam filter CASS 2.0 version.  In our case if we turned the spam filter off the mail would come in.  What we ended up doing was whitelisting in a sense.  Simple whitelisting of the domains in the anti-spam did not work.  In the SonicWall firewall we did the following.

1. We identified the IP addresses of the barracuda servers hosting the O365 clients.
2. In the SonicWall under the Network option we added the IP address entries as address objects
3. We added barracudanetworks.com resolving to *.barracudanetworks.com to cover the whole domain in case the IP address entry changed.
4. We also added the domains of the O365 clients to the address objects.
5. Going to the Anti-Spam selection we went to Settings and then User defined Access List and added the entries from the address objects to the Allow Client List.

This solution has worked for us allowing the O365 mail to come in.  I don’t know if your situation matches mine with the SonicWall involved but hopefully this may help.

Thanks.

Averell