RainLoop Webmail

RainLoop Webmail is a web-based email client that connects directly to mail servers over IMAP and SMTP, so messages are not stored on the web server. It requires no database backend except for contacts, has modest system requirements, and offers simple installation and upgrades.

It supports multiple accounts and identities, Sieve scripts for filters and vacation messages, IMAP extensions including QUOTA, CONDSTORE, SORT and MOVE, and SSL and STARTTLS. Features include a multi-level caching system, visual themes, a multi-language interface, drag-and-drop for messages and attachments, keyboard shortcuts, address autocompletion, and rendering of complex HTML mail. An administrative panel handles configuration and plugin installation, with an upgrade tool built into the admin interface. Integrations cover Facebook, Google, Twitter and Dropbox, and security features include Client Side OpenPGP, two-factor authentication, HTML sanitization and CSRF protection.

It runs on PHP 5.4 or later with a few extensions. The pages refer to a Standard edition in connection with the admin upgrade tool; no other editions or pricing details are stated.