I'm now a spam originator ... Apparently

So apparently there is now a spam bot(net) out there (at 88.232.98.61, 92.81.250.109, among others) that has harvested my work email as a sender address.
This means that I'm getting about 2 or 3 bounce messages per hour telling me that "the addresses was unreachable" and that "our bulk email filter has rejected you email" etc. Lucky for me I seem to be mostly selling watches.

But I'm pretty frustrated because there doesn't seem to be a solution and if this goes on for much longer my address (and/or company domain) is going to make it onto some official spam black lists... which will prevent me from getting (real) emails to any one.
Bah!

Does any one have any ideas? I personally think I'm just screwed. I just wish I knew where they're harvested my address from. I don't even get that much spam normally, I'm pretty defensive about where I give it out.
<sigh>