RainLoop is a simple, modern and fast web-based email client written in PHP. It provides an AJAX-powered webmail interface that connects to any IMAP/SMTP server, with support for multiple accounts, plugins and themes. It was one of the most popular lightweight webmail front ends of the 2010s and is still bundled by many hosting control panels.

Project Status — Archived

RainLoop is no longer actively maintained. Its GitHub repository has been archived and the final release (v1.17.0) shipped in August 2022; security fixes and feature development have stopped. For new deployments, use SnappyMail, the actively maintained fork that continues the RainLoop codebase.

Key Features

• AJAX interface — responsive, desktop-like webmail with instant navigation.
• Multiple accounts — sign in to several IMAP/SMTP accounts from one interface.
• Plugin and theme system — extend functionality and restyle the interface.
• Admin panel — centrally manage domains, accounts and settings.
• Standard IMAP/SMTP — works with any standards-compliant mail server.
• Two-factor authentication — optional TOTP login for the web interface.

Why Consider It?

RainLoop remains a lightweight, familiar webmail interface and is still functional for existing installations that are not exposed to untrusted networks. However, because it receives no security updates, it should not be chosen for new self-hosted deployments.

Open Source Alternative

• SnappyMail — actively maintained fork of RainLoop (AGPL-3.0)
• Roundcube — widely deployed GPL PHP webmail client

Platform

Web (PHP 7.0+ with the IMAP extension, served by nginx or Apache).

Licence

MIT — free and open source software (unmaintained; see project status above).

Website

rainloop.net · GitHub