Greylisting

Installation

pacman -S postgrey

Activate configuration

cp /usr/lib/systemd/system/postgrey.service /etc/systemd/system/

Add to Postfix configuration

/etc/postfix/main.cf

smtpd_recipient_restrictions =
	check_policy_service inet:127.0.0.1:10030

Add automated whitelist

/etc/systemd/system/postgrey.service

ExecStart=/usr/bin/postgrey --inet=127.0.0.1:10030 \
	--pidfile=/run/postgrey/postgrey.pid \
	--group=postgrey --user=postgrey \
	--daemonize \
	--greylist-text="Greylisted for %%s seconds" \
	--auto-whitelist-clients=5

systemctl deamon-reload
systemctl restart postgrey