Mox Email Server

Mox Email Server

Mox is a modern, self-hosted email server written in Go. This skill covers installation, Caddy integration, and administration.

Quick Reference

Installation Workflow

1. DNS Setup - Configure A, MX, SPF, DMARC records

   • See dns-records.md

2. Install Mox - Download binary, run quickstart

   • See administration.md

3. Configure for Docker - Add Docker bridge IPs, set up listeners

   • See mox-config.md

4. Caddy Integration - Reverse proxy, certificate sync

   • See caddy-integration.md

5. Create Accounts - Admin UI or CLI

   • See administration.md

Architecture: Caddy + Mox

Internet → Caddy (Docker, ports 80/443) → Mox (Host, port 8080) [Web UI]
Internet → Mox (Host, ports 25/465/587/993) [SMTP/IMAP]

Caddy handles:

• TLS certificates via ACME
• Reverse proxy for web interfaces (admin, webmail, autoconfig, MTA-STS)

Mox handles:

• SMTP (25), SMTPS (465), Submission (587), IMAPS (993)
• Web interfaces on port 8080

Certificate sync: Caddy obtains certs → systemd timer copies to Mox → Mox uses for SMTP/IMAP TLS.

Critical Configuration Points

Docker Bridge IPs in mox.conf

Mox internal listener must include Docker bridge IPs for Caddy to reach it:

internal:
    IPs:
        - 127.0.0.1
        - ::1
        - 172.17.0.1
        - 172.18.0.1
        - 172.19.0.1
        - 172.20.0.1
        - 172.21.0.1
        - 172.22.0.1
    Hostname: localhost

Caddyfile Admin Path

Admin interface requires Host header rewrite:

handle /admin/* {
    reverse_proxy host.docker.internal:8080 {
        header_up Host localhost
    }
}

UFW Firewall Rule

Allow Docker-to-host communication:

sudo ufw allow from 172.16.0.0/12 to any port 8080 comment 'Docker to mox'

Reference Files

Health Check

Run the included health check script:

sudo scripts/mox-health-check.sh [PUBLIC_IP]

Checks: service status, port connectivity, certificate validity, configuration, recent errors.