Mail-in-a-Box

Mail-in-a-Box is an open-source setup script that turns a fresh Ubuntu 22.04 x64 cloud machine into a working mail server, letting individuals and organizations run their own email service rather than relying on a third-party provider. It handles the configuration of the many protocols surrounding modern email, providing a turn-key system with limited configuration options.

The box includes Roundcube webmail, an IMAP/SMTP server, and Nextcloud contacts and calendar synchronization. Standard mail functionality covers spam filtering and greylisting, mail filter rules, email client autoconfiguration, and automated backups to Amazon S3 and other services. Automatic DNS configuration sets records such as SPF, DKIM, DMARC, and MTA-STS, with optional DNSSEC and DANE TLSA, while TLS certificates are provisioned from Let's Encrypt. A web-based control panel manages mail accounts, aliases, custom DNS records, and backups, with status checks, TOTP two-factor authentication, and a RESTful HTTP API. The system supports multiple users and domain names, plus simple static website hosting.

Mail-in-a-Box is aimed at users who want to operate their own mail service on a cloud server, including those without deep technical expertise, though it is not designed for extensive customization. It is released under the CC0 public domain dedication and is available at no cost.