What is blacklist?

Blacklist is a database of computer IP addresses or e-mail addresses that are known to be used for sending unsolicited emails often referred to as spam, or to generate artificial malicious traffic that is used to execute DDoS attacks.

The purpose of a blacklist is to minimize the impact of spammers and hackers on the genuine Internet users, and to keep the volume of spam low.

There are several free online blacklist databases that are used by ISPs, email companies and email client software to stop unwanted spam messages. Spam can be blocked at the time it is being sent off, or when it tries to reach the victim's mailbox.