How to enable/disable greylisting on OS X 10.10 Yosemite and OS X 10.11 El Capitan With Server 5?
Click here to learn more about greylisting.
To disable greylisting:
sudo serveradmin settings mail:postfix:greylist_enabled = no
sudo /Applications/Server.app/Contents/ServerRoot/usr/sbin/postfix reload
To enable greylisting:
sudo serveradmin settings mail:postfix:greylist_enabled = yes
sudo /Applications/Server.app/Contents/ServerRoot/usr/sbin/postfix reload