Top MAIL GitHub Repositories & Tools (2026)

Built from the ground up for speed. Flectar Mail delivers native performance, instant startup, and as little as 20 MB of RAM.

Macro is a unified workspace for teams: email, chat, docs, tasks, agents, calls, and CRM — @-linked together with shared AI memory.

Thunderbird for Android – Open Source Email App for Android (fka K-9 Mail)

💌 Build and send emails using React

A self-hosted, unified webmail client.

🧑‍🚀 Authentication and authorization infrastructure for SaaS and AI apps, built on OIDC and OAuth 2.1 with multi-tenancy, SSO, and RBAC.

Low code web framework for real world applications, in Python and Javascript

Self-hosted mail server for your own domain: SMTP/IMAP/POP3, CardDAV/CalDAV, React webmail and admin console, one-command Docker Compose.

Cypht: Lightweight Open Source webmail aggregator [PHP, JS]. Supports IMAP/SMTP, JMAP and EWS (Exchange Web Services)

FreeScout — Free self-hosted omnichannel AI-powered helpdesk & shared mailbox

Rallly is an open-source scheduling and collaboration tool designed to make organizing events and meetings easier.

A cross-platform .NET library for IMAP, POP3, and SMTP.

:mailbox: SMTP Server + Web Interface for viewing and testing emails during development.

EspoCRM – Open Source CRM Application

Juice inlines CSS stylesheets into your HTML source.

Privacy-first password manager with built-in email aliasing. Fully encrypted and self-hostable.

120 marketing skills as an AI marketing staff — plugin, portable skills, or an 8-bot team across 7 disciplines (narrative, SEO/GEO, social, email, paid, influencer, launch) on one contract, with 8 auditor gates: TALE · CORE-EEAT · CITE · ECHO · SEND · ROAS · STAR · RAMP.

:mailbox: Cross-language temporary (disposable/throwaway) email detection library. Covers 55 734+ fake email providers.

Unofficial ProtonMail Desktop App

Collection of RSpec/MiniTest matchers and Cucumber steps for testing email in a ruby app using ActionMailer or Pony