sudo apt-get install libmail-gnupg-perl libmime-tools-perl libconfig-auto-perl Also, Fripost's schema (module Fripost::Schema) needs to be found in the library path. addgroup mklist adduser list mklist adduser schleuder mklist mkdir -m 0700 -p /etc/mklist/gnupg-{mailman,schleuder} chown 'list:list' /etc/mklist/gnupg-mailman chown 'schleuder:schleuder' /etc/mklist/gnupg-schleuder cp ./config /etc/mklist/ mkdir /etc/postfix-lists/{mailman,schleuder} chown list:list /etc/postfix-lists/mailman chown schleuder:schleuder /etc/postfix-lists/schleuder To add a key: ggp --homedir /etc/mklist/gnupg --import < /path/to/pubkey.pub for each list manager. For instance, sudo -u www-data gpg --homedir /etc/fripost-panel/gnupg/ -a --export ECFA6E43 | sudo -u list gpg --homedir /etc/mklist/gnupg-mailman/ --import sudo -u www-data gpg --homedir /etc/fripost-panel/gnupg/ -a --export ECFA6E43 | sudo -u schleuder gpg --homedir /etc/mklist/gnupg-schleuder/ --import (Don't forget to whitelist the key ID in the configuration file.) Postfix's lookup table (/etc/postfix-lists/transport_mklist) mklist#fripost.org+mailman@lists.fripost.org mklist-mailman: mklist#fripost.org+schleuder@lists.fripost.org mklist-schleuder: Postfix's master.cf mklist-mailman unix - n n - - pipe flags=FR directory=/opt/fripost-panel/ user=list:list argv=/opt/fripost-panel/misc/mklist/mklist.pl mailman ${size} mklist-schleuder unix - n n - - pipe flags=FR directory=/opt/fripost-panel/ user=schleuder:schleuder argv=/opt/fripost-panel/misc/mklist/mklist.pl schleuder ${size} Postfix's main.cf transport_maps = cdb:$config_directory/transport_mklist cdb:$config_directory/mailman/transport cdb:$config_directory/schleuder/transport mklist-mailman_destination_concurrency_limit = 1 mklist-mailman_destination_recpipient_limit = 1 mklist-mailman_time_limit = 10m mklist-schleuder_destination_concurrency_limit = 1 mklist-schleuder_destination_recpipient_limit = 1 mklist-schleuder_time_limit = 2h