I've got a client who has Exchange 2007 on site and they use Symantec Message Labs for their filtering.
I've got one supplier, who keeps getting blocked.
It's no longer being blocked by the Message Labs system. I can see it being delivery.
However it is being blocked by the server. The Messages Labs system is saying it is being blocked by the 'Content Filtering'.
On the server I've added the domains on the Exchange Management console to:
Organization Configuration > Hub Transport > Anti-Spam > Content Filtering.
I've also done an MXToolBox lookup for the IP addresses of these servers and added them to:
Organization Configuration > Hub Transport > Anti-Spam > IP Allow List Providers
Server Configuration > Hub Transport > Anti-Spam > IP Allow List
I've restarted the server afterwards but the emails are still being blocked.
There isn't any AV blocking them either.
Any other ideas?