Install bley by entering the following commands in the terminal:
sudo apt update sudo apt install bley
Description:
intelligent greylisting daemon for Postfix and Exim
bley uses various tests (incl. RBL and SPF) to decide whether a sender should be greylisted or not, thus mostly eliminating the usual greylisting delay while still filtering most of the spam.
Homepage: http://bley.mx
Version: 2.0.0-2
Section: universe/mail