docker-mailserver — Production-Ready Self-Hosted Email in Docker

Introduction

Running your own email server has a reputation for being complex. docker-mailserver packages the entire stack into a single container image with sensible defaults, so you can self-host email for a custom domain with SMTP, IMAP, spam filtering, DKIM signing, and TLS in a few minutes.

What docker-mailserver Does

• Provides SMTP (Postfix) and IMAP (Dovecot) in one container
• Includes spam filtering via SpamAssassin and optional ClamAV virus scanning
• Handles DKIM, SPF, and DMARC signing and validation automatically
• Supports multiple domains and virtual mailbox users
• Ships a setup.sh CLI for managing accounts, aliases, and DKIM keys

Architecture Overview

The container runs a supervisor process that manages Postfix, Dovecot, OpenDKIM, Amavis, and optional services like Fail2Ban and Fetchmail. Mail data, state, and configuration are stored in three bind-mounted volumes. Environment variables control which features are enabled, and the setup CLI writes config files inside the container that persist via volumes.

Self-Hosting & Configuration

• Requires Docker or Podman and a host with ports 25, 143, 587, and 993 open
• DNS must have MX, SPF, DKIM, and DMARC records pointing to the server
• TLS certificates can be provided manually or obtained via Let's Encrypt integration
• User accounts and aliases are managed with setup.sh email add user@domain
• All tuning is done through environment variables in the Compose file

Key Features

• Single-container deployment with no external database dependency
• Built-in Fail2Ban for brute-force protection on SMTP and IMAP
• Automatic DKIM key generation and DNS record guidance
• Optional Fetchmail support for pulling from external accounts
• Active community with detailed documentation and quick issue response

Comparison with Similar Tools

• Mailcow — Full web UI with SOGo groupware; docker-mailserver is leaner with no web interface
• Mail-in-a-Box — Ubuntu-based all-in-one server; docker-mailserver runs in containers for easier isolation
• Mailu — Python-based containerized mail; docker-mailserver uses traditional MTA components (Postfix/Dovecot)
• iRedMail — Installs directly on a VM; docker-mailserver offers a more portable container-native approach

FAQ

Q: Do I need a static IP to run a mail server? A: Yes. Most receiving servers check reverse DNS, so a static IP with a matching PTR record is essential for deliverability.

Q: Can I use this with an external SMTP relay like SendGrid? A: Yes. Set RELAY_HOST and related environment variables to route outbound mail through a relay.

Q: How do I back up mailboxes? A: Back up the mail-data and mail-state volumes. Mailbox data is stored in standard Maildir format.

Q: Does it support LDAP for user accounts? A: Yes. LDAP authentication is supported as an alternative to the built-in file-based user management.

Sources

• https://github.com/docker-mailserver/docker-mailserver
• https://docker-mailserver.github.io/docker-mailserver/latest/