A couple of times a month, someone either asks me how to return email to the sender or they take exception to my article that says this is a really bad idea and let me know, in no uncertain terms, that I'm wrong.
Can I create a rule for an email address so that if they send me email it will trigger an automated response that there email is rejected? Sort of like blocking callers. I hate going to my junk mail box to find stray messages, only to find this scary person's emails there.
No, you can't do this and it's a really bad idea. Technically speaking, rejection can only be done during the SMTP transaction, as your server is handed the message from the sending server. Once the gateway SMTP server has accepted email for delivery, the message is considered delivered and any savvy sender will know a fake reject from the real thing.
Responding to a spammer does one of two things: it lets them know your address is valid or the response bounces and adds another message (the NDR) to your Inbox that needs to be handled. If the message doesn't bounce back and you're lucky, the message lands in an unmonitored mailbox; unlucky is the spammer resells your address as "guaranteed valid" and you get a lot more spam.
The smart thing to do: just delete the spam. If you don't want it in the junk mail folder, use a rule to delete the messages.