Stuck With Spoofed Email Sh*t

A month back there was a posting here on BHW about a website which offers a free service of sending out emails with your ad attached. It looked like some sort of email opt-in service where members promote their own stuff to each other so it looked legit. So I went ahead to plonk in a test ad - and made the mistake of registering my main email. Now my email is being spoofed as the sender for tons of crap being blasted everyday I think. I get some of these coming back to me ("me" sending to me - yes).

I tried changing my email password but that didn't help in stopping it. I can't kill off the email cos its not a free email but my corporate domain email linked to uncountable registries.

Yes it is a dumb mistake and I have no idea how to turn off the tap as I can't find that thread on BHW and can't find that bl**dy website.

I feel like a dickhead already so please don't give me further grief - please give me advice. Really appreciate it!!!