Official Lark/Feishu CLI tool with 200+ commands and 26 AI agent skills, designed for agent-native operation and easy integration with AI runtimes.

Production-ready fullstack but simple mail server (SMTP, IMAP, LDAP, Antispam, Antivirus, etc.) running inside a container.

:love_letter: A beautiful, fast and fully open source mail client for Mac, Windows and Linux.

Mail-in-a-Box helps individuals take back control of their email by defining a one-click, easy-to-deploy SMTP+everything else server: a mail server in a box.

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

A Cloudflare-based email service | 基于 Cloudflare 的邮箱服务 | Cloudflare Email 邮箱 Mail

Experience email the way you want with Mail0 – the first open source email app that puts your privacy and safety first. Join the discord: https://mail0.link/discord

Insular email distribution - mail server as Docker images

✉️ Composable all-in-one mail server.

📧 Easy to use, yet comprehensive library for sending mails with Go

Mail hosting made simple

Full-featured, open source mail server solution for mainstream Linux/BSD distributions.