said by NormanS:You got me curious. Looks like there are actually TONS of open relays (unfortunately) »
Ah, that makes senses. None of the big providers, ISP or otherwise, run open relays. Heck, I run a mail server on my residential connection and I have secured it against relay. There may be even as many as 100 open relays on the entire Internet. Oh, and I will add a hyperbole warning on that number. I have no way to determine a realistic estimate. About once every month, or so, I see attempts at unauthorized relay; I have to presume that the spammers will find one almost as fast at it appears.