Is there a way to block certain email addresses to a domain from the server to stop them getting through to any of our domains?
I am on a VPS server if that helps any.
To stop them doing what? Emailing you? If you are taking about accessing your site, then no. But you could block by IP.
Sorry i mean to block certain email addresses from emailing a domain.
You should be able to do that. What are you using for email on the server, and are you using a control panel?
The control panel is Kloxo.