Installing dockerized Mailcow with custom ssl certificates

1. Follow official instructions

1. Prepare system.
2. Clone Mailcow repository.
3. Run generate_config.sh.

2. Use custom certificates (ref)

Generate SSL certificates manually e.g. using Certbot

Create docker-compose.override.yml file as follows:

version: '2.1'

services:
  dovecot-mailcow:
	volumes:
	  - ./data/assets/ssl:/etc/ssl/mail/:rw
	  - /mycerts/fullchain.pem:/etc/ssl/mail/cert.pem:ro
	  - /mycerts/privkey.pem:/etc/ssl/mail/key.pem:ro
		#- /opt/data/nginx/certs/dhparam.pem:/etc/ssl/mail/dhparams.pem:ro
  postfix-mailcow:
	volumes:
	  - ./data/assets/ssl:/etc/ssl/mail/:rw
	  - /mycerts/fullchain.pem:/etc/ssl/mail/cert.pem:ro
	  - /mycerts/privkey.pem:/etc/ssl/mail/key.pem:ro
  nginx-mailcow:
	volumes:
	  - ./data/assets/ssl:/etc/ssl/mail/:rw
	  - /mycerts/fullchain.pem:/etc/ssl/mail/cert.pem:ro
	  - /mycerts/privkey.pem:/etc/ssl/mail/key.pem:ro

Replace /mycerts/ with the directory where the certificates e.g.:

• /etc/letsencrypt/archive/...
• Caddy: /var/lib/caddy/.local/share/caddy/certificates/...

Now, disable ACME. In mailcow.conf, set

```
SKIP_LETS_ENCRYPT=y
```

3. Nginx Proxy Manager

• Change ports in mailcow.conf, e.g.

  HTTP_PORT=8080
  HTTP_BIND=127.0.0.1
  

• If using Nginx Proxy Manager without network_mode: host, then we need to add nginx-mailcow to the network. In this case, we add the following to the docker-compose.override.yml above:

  services:
  nginx-mailcow:
    networks:
      - frontend
  networks:
  frontend:
    external: true
  

Change the network frontend accordingly.

• We also have to increase Nginx buffer size for the web interface to work correctly (ref). Add the following to the Nginx reverse proxy config:

  proxy_buffer_size 128k;
  proxy_buffers 64 512k;
  proxy_busy_buffers_size 512k;