How to block whole domain?

How to block whole domain?

I am getting at least 50-75sometimes over 100 spams emails a day. I see a lot of the spam is coming from .eu domains. I would like to block /reject all email coming for the .eu domain. I do not have any need for email from .EU domains. Why won't the BlackList Domain allow a wild card for the entire domain *.EU  and others  such as *.RU  etc.