I don't believe its possible to exclude a specific sender, but you can exclude specific signatures. So, if a sender triggers a specific signature each time you can add a clam whitelist for that signature which should prevent their messages being caught in the future. You can find more information on whitelist setup for Clam AV here: 

Hello Kyle,

yes I already use signatures, but I wanted to know if there was a possibility in SM (CLAM or other active antivirus) to exclude one or more domains from the antivirus scan.

Could it be integrated as a feature?

Thanks

Best Regards

Mark