The concept of whitelist corresponds to "blacklist".

If a whitelist is set up, users (or IP addresses, IP packages, emails, etc.) in the whitelist will be given priority and will not be rejected as spam. This is both safer and faster. Greatly improved.

The white list is to set the users who can pass. Users outside the white list cannot pass. The blacklist is to set users who cannot pass, and users outside the blacklist can pass.

So generally the whitelist restricts more users than the blacklist.

Blacklist source:

The word blacklist comes from the world-famous British universities such as Oxford and Cambridge.

In the early Middle Ages, these schools stipulated that for students who committed misbehavior, their names and actions would be recorded in a black book. Whoever's name was in the black book would be infamous for life, even if it was not , and it will also discredit a person for a considerable period of time.

Students are very afraid of this rule of the school and are often cautious to prevent deviant behavior.