I'm pulling my hair out with a problem here. I'm running Exim 4.05 on a Slackware 8.1 box. Exim has never let me down, but now I have a problem that I need it to solve, and I don't think that it can. I'd appreciate any help you could give me.

Here's the situation. I want to be able to "bounce" messages selectively from a particular e-mail address. Not every address on a domain, but *one* e-mail address. If anyone else sends me an e-mail, I want to get it. If the person at this one particular e-mail address sends me an e-mail, I want Exim to generate a 550 as if my e-mail address doesn't actually exist. I guess in that case the sender's ISP's mail server generates the bounce message, but I want Exim to just act like my account doesn't exist, only when I get mail from this address.

The closest I've gotten is this .forward file in my home directory:

# Exim filter

if $sender_address contains "emailtoblock@server.com" then
 seen finish

However, this only "dumps" the message silently. I don't see anything, but neither does the sender.

Is it possible to do this? I really don't see why it wouldn't be. I would also be happy with a 'global' block, where all mail to my domain from this guy would be bounced.

(FYI, I need an answer to this - it's a little complicated, but "just complain to his ISP" isn't an acceptable solution in this situation.)