Setup Your Own Email Server with Docker

Introduction

For this guide we're going to use docker compose. Docker compose will allow us to neatly configure all parameters, including setting up separate docker volumes for storing data.

Step 0: Setup Domain Records & Create SSL Certs

See your web hosting service for how to set up A & MX records. For example, DigitalOcean users can follow Digital Ocean's tutorial.

See the SSL Configuration guide to setup SSL if you don't have certificates already.

Step 1: Download docker images

We'll be basing our mail server off of docker-mailserver. We'll also be setting up a web client using rainloop. First step is to download the docker images:

docker pull tvial/docker-mailserver:latest  
docker pull krishath/rainloop-ssl:latest  

Step 2: Create docker-compose file

Create a file named docker-compose.yml in the root directory of your email project.
In this file, we'll start with the following configuration:

version: '2'  
services:  

Step 3: Add data volumes

We'll want to store our data in docker data volumes, which will keep them isolated from containers, yet still easily sharable.

volumes:  
  maildata:
    driver: local
  mailstate:
    driver: local

Step 4: Add docker-mailserver configuration

We'll be calling our docker-mailserver container mail.

  mail:
    image: tvial/docker-mailserver:latest
    hostname: {your_hostname}
    domainname: {your_domain}
    container_name: mail
    ports:
    - "25:25"
    - "143:143"
    - "587:587"
    - "993:993"
    volumes:
    - maildata:/var/mail
    - mailstate:/var/mail-state
    - mailconfig:/tmp/docker-mailserver/
    - {path_to_ssl}:/etc/letsencrypt/
    - /etc/localtime:/etc/localtime:ro

You'll need to fill in {your_hostname}, {your_domain}, {your_FQDN}, and {path_to_ssl} with your own configuration.

For example, if your domain MX record was pointed to mail.example.com:

• {your_hostname} would be mail,
• {your_domain} would be example.com
• {your_FQDN} would be mail.example.com.

Step 5: Add rainloop configuration

We'll be calling our rainloop container webmail. Under services:, add the following configuration.

  webmail:
    image: krishath/rainloop-ssl
    container_name: webmail
    volumes:
    - {path_to_ssl}/etc/live/{your_FQDN}/fullchain.pem:/etc/ssl/cert.pem
    - {path_to_ssl}/etc/live/{your_FQDN}/privkey.pem:/etc/ssl/cert.key
    - {path_to_ssl}/dhparam.pem:/etc/ssl/certs/dhparam.pem
    - webmaildata:/webapps/rainloop/data
    - /etc/localtime:/etc/localtime:ro
    ports:
    - "443:443"

Step 4: Bring up the containers

Now that everything should be configured correctly, bring up the docker containers with:

sudo docker-compose up -d  

The -d option starts the containers in the background.
You can stop the containers at any time with sudo docker-compose down.

Step 5: Verify everything is working

Now confirm that the containers are running pointed to the correct directories with:

docker inspect mail  

This will inspect the mail container we brought up with docker-compose. You should see the volumes you created references under "Mounts".
Also confirm that we can connect to the mail server using ssl:

openssl s_client -showcerts -connect {your_hostname}:993  

Step 6: Create an email account

Use the setup script to add an email account to your new mail server:

./setup.sh  -c mail email add email@example.com

Step 7: Connect to your mail server using rainloop

Try to connect to your webserver's admin page. i.e. https://webmail.example.com/?admin After you login use the default username and password (admin, 12345), immediately change the admin password to something more secure (under "Security").

Now, Setup the connection to your mail server by adding a new domain (under "Domains").

Test the configuration - at this point, you should be able to go to login to your email using `https://webmail.example.com/.