Blocking one of your Email Addresses

When I visit a Web page, I sign up for theirdomainname@mydomainhere.com. This way if I ever get spam, I know EXACTLY who gave out my list. This so far has happened twice. The first time the company apologized because someone had in fact hacked their servers and stole their list. They also gave me a $50.00 product of my choice free of charge. The next company to do this, has blamed me for this mishap, even though I get multiple spams with theirname.net@mydomainhere.com. They have no explanation for it. I just want them to stop, and admit they were wrong. Anyhow, my question, I need to set up that email addres so it bounces. I can set it up so it routes to a null spot, but that doesn't create a bounce message does it? The problem is I use a catch all alias, @mydomain.com -> my email address. It is sendmail, and sorry im not sure on the version.

When I said EXACTLY who gave out my list, I meant email.

Before the catchall line in your virtusertable, add something like:

theirname.net@mydomainhere.com error:nouser No such user here

that should bounce that address, but allow other address @mydomainhere.com to go to the catch all....