Real-Time Blacklist (RBL)
Real-Time Blacklists(RBL) is a list of IP address owners that are active spammers or spam sources.RBL is known to be used as a defence for IP addresses against spam.

DooxMail’s Real-Time Blacklist (RBL) blacklist check will test a mail server IP address against over 64 known email blacklists. If your mail server or IP has been blacklisted, some emails that you send may not be delivered.

The DooxMail Tools RBL section allows you to manage users by adding IP address lists and checking if an IP address is blacklisted.