WHAT IS IT?
BillionMail is an open-source mail platform that bundles a full email server with marketing campaign tools in a single Docker deployment. Under the hood: Postfix handles SMTP, Dovecot takes care of IMAP, Rspamd filters spam, and RoundCube provides webmail. The whole thing is written in Go (92% of the codebase), stores data in a SQL database, and is managed through a web admin interface.
Installation runs through docker compose up -d or a simple bash install.sh. In under 10 minutes you get a working mail server with campaign management, list handling, and analytics. The project is AGPL-3.0 licensed, has over 13,700 GitHub stars, and is currently at version 4.9.
WHY IS IT INTERESTING?
No per-email metering. BillionMail has zero built-in sending limits. You pay for your server, you send what you want. No billing tiers, no end-of-month surprises. For high-volume senders, this fundamentally changes the cost equation compared to Mailchimp or SendGrid.
Guided DNS and deliverability. The admin interface walks you through SPF, DKIM, and DMARC configuration step by step. SSL certificates are provisioned automatically. The dashboard displays sent volume, deliverability rate, open rate, and click-through rate in real time. When an email bounces, you know exactly why.
Native email campaigns. Reusable template editor, list segmentation, variable personalization, spintax support, scheduled sending. This is a full campaign tool baked into the server, not a plugin bolted on after the fact.
Webmail out of the box. RoundCube is accessible at /roundcube/ from the moment you deploy. Users can read and send mail from the browser with zero client setup.
Three deployment paths. Docker Compose, bash script, or one-click install via aaPanel. A CLI tool (bm) handles credential management, DNS record display, and system updates.
USE CASES
- Send high-volume newsletters without SaaS dependency or per-email pricing
- Host team or organization email on your own domain with built-in webmail
- Handle transactional emails (signup confirmation, password reset) on your own infrastructure
- Run outreach campaigns with deliverability tracking and engagement metrics
- Replace a hand-wired mail stack (Postfix + Dovecot + custom scripts) with an integrated solution