Randomize Source IP Addresses With Postfix Rumi, August 19, 2026 Enters Postfix version 3. It introduced a new randmap table which made this much easier to accomplish. In main.cf, just add the following lines sender_dependent_default_transport_maps = randmap:{relay1,relay2,relay3,relay4,relay5} smtp_connection_cache_on_demand=no Those lines have 2 effects: Randomly select an SMTP client for sending each email Prevent the SMTP clients from caching connections, so sending multiple emails to… Continue Reading