on this page
email-fundamentals/ — concepts that apply regardless of MTA¶
- Email Architecture — MUA/MTA/MDA roles, envelope vs. headers, ports
- The SMTP Protocol — the raw conversation, response codes, STARTTLS vs. implicit TLS, bounces
- DNS and Mail Routing — MX/PTR records, relaying vs. final delivery, smart hosts
- Email Authentication and Anti-Spam — SPF, DKIM, DMARC, RBLs, greylisting concept
- Mailbox Formats and Delivery — mbox vs. Maildir, local vs. virtual mailboxes, MDAs
postfix/ — Postfix-specific¶
- Overview and Architecture — the daemon pipeline, queue directories, lookup table types, core identity settings
- Installation and Basic Configuration — install, minimal
main.cf, testing via mail/telnet
- Relaying Outbound Mail — null client pattern, daemonless submission with
msmtp (e.g. feeding an existing containerized Postfix relay), relaying via Gmail/Mailgun/Proton Mail/generic smart hosts
- Virtual Domains, Mailing Lists, and Virtual Mailboxes — forwarding domains,
/etc/aliases lists, MySQL-backed virtual mailboxes, PostfixAdmin, auto-reply
- TLS Encryption — security levels, per-domain enforcement, certs, verification, troubleshooting
- Security and Hardening — open relay testing, greylisting (postgrey), header/content filtering, checklist
- Administration and Queue Management —
postqueue, postsuper, aliases, logs
- Troubleshooting — reading log severities, a catalog of specific errors and fixes
- Legacy Reference: Two-Host Local Network Setup — historical home-network relay setup, kept for reference