Step-by-step guide to installing and configuring Postfix as an SMTP mail transfer agent on Ubuntu. Covers initial installation via APT with interactive configuration, setting up Maildir format, virtual alias mapping, and testing with s-nail. Also includes send-only configuration for applications and monitoring systems, TLS encryption setup with Let's Encrypt, and a comprehensive troubleshooting section covering log interpretation, mail queue management, port 25 restrictions, DNS authentication records (SPF, DKIM, DMARC), and relay access issues.
Table of contents
IntroductionPrerequisitesWhat is Postfix?Step 1 — Installing PostfixStep 2 — Changing the Postfix ConfigurationStep 3 — Installing the Mail Client and Initializing the Maildir StructureStep 4 — Testing the ClientConfiguring Postfix as a Send-Only SMTP ServerEnabling TLS Encryption for Secure SMTPTroubleshooting Postfix and Mail DeliveryFAQsConclusionSort: