Postfix / Courier SMTP and IMAP Image

Email server in Docker based on Postfix and Courier.

This image provides an email server, serving IMAPS and SMTP(S) endpoints. SSL configuration is mandatory.

Authentication is handled by Courier's userdb. Postfix refers to users configured in Courier via the rimap option.

Configuration

You must provide an environment variable MAIL_DOMAIN containing your domain name, e. g. example.org.

All postfix configuration parameters of main.cf (see Postfix Configuration Parameters) may be provided via environment variables prefixed by PF_, e.g. for 2bounce_notice_recipient provide PF_2BOUNCE_NOTICE_RECIPIENT=example.org.

Similarily, Courier's configuration (stored in /etc/courier/imapd-ssl) can be altered through CO_-prefixed environment variables.

On startup, an account named postmaster with password changeme is created. On first startup, you must change it:

docker exec -it mycontainer bash
$ userdbpw -md5 | userdb default/postmaster set systempw

Persistent Data (Volumes)

Emails are stored in Maildir format below /home/vmail. Users are stored below /etc/courier/userdb/. You probably want to add volumes for these two folders.

Basic Setup

Here is a sample compose file using Let's Encrypt certificates from your host:

version: '2'

services:
  mail:
    image: topheee/postfix-courier-mail:1.0
    environment:
    - MAIL_DOMAIN=example.org
    - PF_MYDOMAIN=example.org
    - PF_MYHOSTNAME=example.org
    - PF_SMTP_TLS_CERT_FILE=/etc/letsencrypt/live/example.org/fullchain.pem
    - PF_SMTP_TLS_KEY_FILE=/etc/letsencrypt/live/example.org/privkey.pem
    - PF_SMTPD_TLS_CERT_FILE=/etc/letsencrypt/live/example.org/fullchain.pem
    - PF_SMTPD_TLS_KEY_FILE=/etc/letsencrypt/live/example.org/privkey.pem
    volumes:
    - "maildir:/home/vmail"
    - "userdb:/etc/courier/userdb/"
    - "/etc/letsencrypt/:/etc/letsencrypt/:ro"

    ports:
      # imaps
      - 993:993/tcp
      # smtp
      - 25:25/tcp

volumes:
  maildir:
  userdb:

Notes

This project is licensed under the terms of the MIT license.