Dummy accounts to block spam

I’ve seen a lot of SPAM solutions – client, server, 3rd party, etc… – and they all have different ways to block spam. I’ve heard of solutions server or gateway side solutions where a “dummy” account is set up, and any email that goes to the dummy account, subsequently gets blocked or ‘spam-tagged’ to all additional accounts.

I’ve heard of the technology, but can’t seem to find the solution on the net. Anybody heard of this?