Protected Sky's RBL utilises advanced IP reputation checks to detect spam.
The RBL base name is 'bad.psky.me'.
For Example, a lookup on 127.0.0.2
User@Host:~$ dig 22.214.171.124.bad.psky.me +short 127.0.0.2 User@Host:~$
The RBL conforms to RFC5782
Currently, the RBL returns the following:
|NOERROR||The IP address is question is fine for sending mail.||Accept the message|
|127.0.0.2||The IP address in question has been seen with a high rate of spam.||Defer the message for later.|
|127.0.0.3||The IP address in question has been seen to have a very high rate of spam.||Reject the message at SMTP submission.|