Install hapolicy by entering the following commands in the terminal:
sudo apt update sudo apt install hapolicy
Description:
Balancing and fallback postfix policy delegation service
Hapolicy enables high availability, weighted loadbalancing and a fallback action for postfix policy delegation services. Invoked via postfix spawn it acts as a wrapper that queries other policy servers via tcp connection. The order of the service queries can be influenced by assigning a specific priority and weight to each service.
Homepage: http://www.postfwd.org/
Version: 1.35-4
Section: universe/mail