I've come across this
outfit. You
don't necessarilly have had to be a spammer (or other config. problem) to be blocked.
I'm not on a network, private email address, single computer, not spamming, all security software functional and effective. No problems with emails to almost anywhere, anyone, anytime.
Had several emails to one friend returned - unable to be delivered, SORBS blocked them, (Ironically for a while I was able to contact the recipient via my Hotmail acct., but not always.)
So I contacted SORBS with the particular ref # supplied, to be told that because
one computer with my ISP's host address had sent spam, no-one from that ISP could get through to the destination ISP, as they had (hired?) SORBS to block all spam. So I replied, explaining the situation, and their reply was I should sort it out with my ISP; they being the "guilty" party, for allowing spam. My own ISP, whilst sympathetic, refused to do business with SORBS because (in a nutshell) it was percieved the way
they did business amounted to cyber-blackmail. Catch22.
End result? My friend, who had had a considerable number of valid emails blocked, and unable to get satisfaction from his ISP, changed ISP's to one who
doesn't use SORBS.
All happy.
Edit PS; Sorbs charges $50 (or did) as a one off payment to have your address de-listed from their database.