Re: Open Resolver Public DNS problem, 8.8.8.8
Hi, a layman's explanation.
Consider the following route that emails follow when Bob emails Joe
Sender (Bob) -> Senders Mail Server (Twiki) -> Receivers Mail Server (Kryten) -> Receiver (Joe)
Bob clicks send
Bob's email is passed to Twiki
Twiki Passes the email to Kryten
Kryten delivers the email to Joe.
- However When a DNSBL is involved
Bob clicks send
Bob's email is passed to Twiki
Twiki informs Kryten an email is ready to be passed to it.
Krytem looks up Twiki on Spamhaus (or other DNSBL) and finds a listing.
Kryten tells Twiki that the email is being rejected, and if configured correctly, gives an accurate reason why.
Twiki tells Bob that the email was rejected, along with whatever reason Kryten gave (if configured)
If anything other than the above occurs, then either Kryten or Twiki is not configured to transport mail according to RFC standards and this is where things go wrong.
So if I read your post above correctly, Bob is emailing Joe, and Joe gets the bounceback notification. This indicates either Twiki or Kryten is configured incorrectly because Bob should be getting the response his email did not get through, This isn't Spamhaus's fault. An admin has configured the mail transport incorrectly on their server.