Summary

Adds a service template for Docker Mailserver, a fullstack production-ready mail server based on Postfix and Dovecot, addressing #8266.

What’s included:

• Docker Mailserver (ghcr.io/docker-mailserver/docker-mailserver:latest) — battle-tested, actively maintained mail server
• Standard mail ports — SMTP (25), IMAP (143), ESMTP with TLS (465, 587), IMAPS (993)
• Persistent volumes — mail data, mail state, logs, and configuration all persist across restarts
• Configurable options — hostname, SpamAssassin, ClamAV, Fail2Ban, Postgrey, SSL type, and more via environment variables
• Health check — monitors SMTP port availability
• SVG logo — simple mail icon for the service listing

Configuration after deployment:

Users will need to:

1. Set MAIL_HOSTNAME to their mail server’s FQDN
2. Configure DNS records (MX, SPF, DKIM, DMARC)
3. Add email accounts via docker exec -it <container> setup email add user@domain.com

Notes:

• The template uses Docker Mailserver as recommended in the issue (over Mailu) for its simpler single-container architecture
• Compatible with Coolify’s proxy and certificate management via the SSL_TYPE environment variable
• SpamAssassin enabled by default, ClamAV disabled by default (resource-intensive)

Closes #8266

/claim #8266