> Interesting idea. Do you have a link to the software you use for that,
> and configuration details? What drawbacks have you run into with this technique?
I probably should have referred to it in the article, but we had some information about Bounce
Address Verification in http://lwn.net/Articles/189531/
I think that is what David is referring to or is something similar. The info in that article
may be getting out of date now, though.