Personal Mail Server

This project is a dead simple solution to configure and use Postfix + OpenDKIM to run a personal mail server.

Install

The recommended way to install this project on your server is to use a docker-compose.yml file (change mail.example.com to your hostname):

services:
  server:
    image: aslrousta/mail:latest
    hostname: mail.example.com
    environment:
      - HOSTNAME=mail.example.com
      - USER=admin
      - PASSWORD=admin
    volumes:
      - ./certs:/etc/postfix/certs:ro
      - ./keys:/etc/dkimkeys
    ports:
      - "25:25"

The mail server generates a default DKIM key for your hostname at initial start-up and puts it in the /etc/dkimkeys/{HOSTNAME} directory. Then, it configures a default mail user with the given USER and PASSWORD environment variables.

In order to use TLS, postfix expects certificates in /etc/postfix/certs directory (fullchain.pem and privkey.pem files) that must belong to your hostname.

DNS Settings

After installation, you have to setup your DNS records properly. Use the contents of default.txt file in /etc/dkimkeys/{HOSTNAME} directory to configure default._domainkey. TXT record.

mail.               IN CNAME     example.com.
@                   IN MX  10    mail.example.com.
@                   IN TXT       "v=spf1 a mx ~all"
_dmarc.             IN TXT       "v=DMARC1;p=quarantine;sp=quarantine;adkim=r;aspf=r"
default._domainkey. IN TXT       "v=DKIM1;h=sha256;k=rsa;p=MIIBIjANBgkq ..."

Then, it must be done and your mail server would be ready to send emails via admin@example.com email address.

Troubleshooting

First of all, check if port 25 is accessible from your network and verify that you see the ESMTP banner. Unless, you might need to configure your firewall settings on SMTP port.

~ telnet mail.example.com 25
Trying ::1...
Connected to localhost.
Escape character is '^]'.
220 mail.example.com ESMTP Postfix (Debian/GNU)

If anything else goes wrong, check /var/log/mail.info and /var/log/mail.err log files in the container.