Apple's mail program let's you block them, and also let's you create rules whereby you can block, move and delete emails based on's someone email address, the subject of the email, who it's to, message content, etc.
I wish they still allowed you to bounce them back to the sender, but they got rid of that option quite a while ago.
Learn a little VBA and it’s no problem. You can send them to as many people as you like.