When you manage Postfix mail servers using SQL connections to find informations about usernames, mailbox/maildir locations on the disk you probably have in your main.cf something like : virtual_alias_maps = mysql:/etc/postfix/mysql_virtual_alias_maps.cf virtual_mailbox_domains = mysql:/etc/postfix/mysql_virtual_domains_maps.cf virtual_mailbox_maps = mysql:/etc/postfix/mysql_virtual_mailbox_maps.cf relay_domains = mysql:/etc/postfix/mysql_relay_domains_maps.cf But, this way, each process(postfix process) uses one MySQL connection.…