Best Open Source Email & Communication Software
Browse 17 production-ready, self-hostable open-source tools in Email & Communication. Eliminate per-seat SaaS costs, retain complete data ownership, and claim $100K+ in startup cloud hosting credits.
Top Open-Source Email & Communication Software Compared
Direct overview of top-ranked solutions by community stars and license
| Tool Name | GitHub Stars | License | Replaces Proprietary | Details |
|---|---|---|---|---|
| Ntfy | ★ 35,000 | Apache-2.0 | Pusher, Firebase Cloud Messaging | View Stack → |
| Billion Mail | ★ 24,109 | AGPL-3.0 | Resend, Mailchimp | View Stack → |
| Plunk | ★ 24,109 | AGPL-3.0 | Resend, Mailchimp | View Stack → |
| useSend | ★ 24,109 | AGPL-3.0 | Resend, Mailchimp | View Stack → |
| Thunderbird for Android | ★ 17,987 | Apache-2.0 | Gmail, Microsoft Outlook | View Stack → |
All 17 Email & Communication Open Source Tools
Ranked by GitHub community stars & active adoption
Ntfy
Apache-2.0A lightweight, open-source solution for sending real-time notifications to your devices, with end-to-end encryption and no sign-up required.
Billion Mail
AGPL-3.0Self-hosted email marketing platform with unlimited sending, AI-powered email creation, real-time analytics, and no monthly fees. Complete SMTP solution.
Plunk
AGPL-3.0Plunk unifies marketing, transactional, and broadcast emails into a single, complete solution for businesses of all sizes.
useSend
AGPL-3.0Open source email platform for transactional and marketing emails. Self-host or use cloud service with transparent pricing - pay only for emails sent.
Thunderbird for Android
Apache-2.0Android email client from the Thunderbird project with unified inbox, multiple account support, OpenPGP encryption, and no ads or data tracking.
Hyvor Relay
AGPL-3.0Self-hosted email API alternative to AWS SES & Mailgun. Open-source AGPL-3.0 with enterprise features, automated deliverability, and cloud version coming 2026.
Sessy
Open SourceTrack SES deliveries, bounces, opens and clicks in a self-hosted dashboard with real-time search, analytics and reputation monitoring.
Wraps
AGPL-3.0Build email templates as React components and automations in TypeScript. Deploy to your AWS account with SES integration. Marketing teams edit content without…
Mailspring
GPL-3.0Desktop email client for Mac, Windows, and Linux with unified inbox, read receipts, link tracking, send later, grammar checking, and contact enrichment.
Inbox Zero
AGPL-3.0Automates Gmail and Outlook with AI-drafted replies, bulk unsubscribe, cold email blocking, attachment filing, and inbox analytics for individuals and teams.
Tuta
GPL-3.0Tuta offers encrypted email, calendar and contacts with quantum-resistant security, protecting your privacy without ads or tracking.
Roundcube
GPL-3.0PHP-based webmail client with MIME support, address book, folder management, threaded views, PGP encryption, and a plugin API for self-hosted email.
UnInbox
AGPL-3.0Streamline team communication with shared inboxes, unlimited email addresses, and customizable workflows. Perfect for modern businesses seeking organized…
Macro Mail
AGPL-3.0An AI-powered email client that combines inbox management, chat, tasks, and AI agents in one shared workspace, built for keyboard-driven workflows.
Postal
MITRun your own mail delivery infrastructure with a web interface, webhooks, IP pools, and spam filtering integrations for inbound and outbound email.
Novu
Open SourceOpen-source platform for building in-app, email, push, SMS, and chat notifications with a unified API, workflow engine, and embeddable inbox component.
Twake Mail
AGPL-3.0Open source professional email solution with PGP encryption, JMAP protocol, AI-powered responses, and advanced antispam protection. Control your data privately.
Frequently Asked Questions: Open Source Email & Communication
What are the best open source Email & Communication tools in 2026?
The highest-ranked open-source software in Email & Communication is Ntfy with over 35,000 GitHub stars. Other leading tools include Billion Mail, Plunk, useSend, Thunderbird for Android. All are vetted for production self-hosting.
Can I self-host Email & Communication open source tools on my own cloud?
Yes. Tools listed in this category support self-hosting via Docker, Docker Compose, Kubernetes, or Helm on AWS, Google Cloud, DigitalOcean, Hetzner, or bare metal with zero per-seat licensing fees.
How can early-stage startups get free cloud credits to host Email & Communication tools?
Founders can claim up to $100,000 in AWS Activate, $350,000 in Google Cloud for Startups, and $1,000 in DigitalOcean credits via Startupbricks Perks (startupbricks.in/perks) to deploy self-hosted stacks at zero infrastructure cost.
What proprietary SaaS does open source Email & Communication software replace?
Open-source tools in this category replace proprietary commercial platforms including Pusher, Firebase Cloud Messaging, Resend, Mailchimp, SendGrid, Brevo, Mailgun, Beehiiv, ActiveCampaign, MailerLite. Switching gives your team 100% data custody, security control, and zero recurring seat costs.
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