Install postgrey by entering the following commands in the terminal:
sudo apt update sudo apt install postgrey
Description:
greylisting implementation for Postfix
This package provides a policy server for Postfix to implement "greylisting". . Greylisting is a spam filtering method that rejects email from external servers on the first try. Spammers don't usually retry sending their messages, whereas legitimate mail servers do. . While Postgrey is designed for use with Postfix, it can also be used with Exim.
Homepage: http://postgrey.schweikert.ch/
Version: 1.36-5
Section: universe/mail