Self-hosted Communication - Email - Mail Transfer Agents

Mail User Agents (MUAs) - Decentralized email clients that enable secure, reliable, and scalable email communication by handling email transfer, encryption, and authentication protocols.

MailCatcher

⭐️ 6.2k

Ruby gem that deploys a simply SMTP MTA gateway that accepts all mail and displays in web interface. Useful for debugging or development.
Haraka

⭐️ 4.9k

High-performance, pluginable SMTP server written in Javascript.
OpenTrashmail

⭐️ 487

Complete trashmail solution that exposes an SMTP server and has a web interface to manage received emails. Works with multiple and wildcard domains and is fully file based (no database needed). Includes RSS feeds and JSON API.
Stalwart SMTP

⭐️ 461

Modern SMTP server designed with a focus on security, speed, and extensive configurability.
DragonFly

⭐️ 222

A small MTA for home and office use. Works on Linux and FreeBSD.
Slimta

⭐️ 170

Mail Transfer Library built on Python.
Sendmail

Message transfer agent (MTA).
Courier MTA

Fast, scalable, enterprise mail/groupware server providing ESMTP, IMAP, POP3, webmail, mailing list, basic web-based calendaring and scheduling services.
Postfix

Fast, easy to administer, and secure Sendmail replacement.
OpenSMTPD

Secure SMTP server implementation from the OpenBSD project.
chasquid

SMTP (email) server with a focus on simplicity, security, and ease of operation.
EmailRelay

A small and easy to configure SMTP and POP3 server for Windows and Linux.
Exim

Message transfer agent (MTA) developed at the University of Cambridge.