jchonig/postfix repository overview

⁠docker-postfix

A container running postfix intended to be used as an internal mail relay to the outside world.

Image hosted at: ghcr.io/jchonig/postfix

Optionally authenticate incoming connections with SASL

⁠Usage

⁠docker

docker create \
  --name=posfix \
  -e PUID=1000 \
  -e PGID=1000 \
  -v </path/to/appdata/config>:/config \
  -p 25:25 \
  --restart unless-stopped \
  ghcr.io/jchonig/postfix

⁠docker-compose

Compatible with docker-compose v2 schemas.

---
version: "2"
services:
  postfix:
    image: ghcr.io/jchonig/postfix
    environment:
      - PUID=1000
      - PGID=1000
    volumes:
      - </path/to/appdata/config>:/config
	  - data:/data
    port:
      - 25
    restart: unless-stopped

volumes:
  data:

⁠Parameters

⁠Ports (-p)

⁠Environment Variables (-e)

⁠Volume Mappings (-v)

⁠Application Setup

• When USE_TLS is enabled, /config/server.cert and /config/server.key should exist
  • When these files are updated, postfix is reloaded automatically
• When RELAYHOST is set, outbound TLS (smtp_tls_security_level=encrypt) is enabled automatically
  • Relay credentials are read from /config/sasl.passwd, which uses standard postfix sasl_passwd format: one entry per line of relayhost user:password
  • Example: [smtp-relay.gmail.com]:587 [email protected]:app-password
  • /config/sasl.passwd is read directly by postfix on demand — no rebuild step needed when the file changes
  • For Gmail Workspace: set RELAYHOST=[smtp-relay.gmail.com]:587 and generate an App Password⁠ for the account; enable the SMTP relay service in Google Workspace Admin → Apps → Gmail → Routing
• When using SASL, /config/sasl.users should should have one entry per line of user and password seperated by a space
  • WHen this file is updated, update_sasldb_users is run automatically
• Additonal postfix configuration can be stored in /config/postconf and /config/postconf.d/*
  • These files contain arguments to the postconf command
  • These files are processed when the container starts
  • These files are reparsed automatically when they are modified or created
  • The files in /config/postconf.d are not processed in a particular order
• Aliases are stored in /config/aliases
  • If this file does not exists the default postfix file is copied to it
  • When this file is updated, newaliases is run

⁠TODO

• Set up DKIM
• Read and process generics and virtual? ...