SquirrelMail

SquirrelMail is a web‑based email client that connects to IMAP servers, allowing users to read, compose, and organize messages through a browser interface. It runs on a self‑hosted web server and is distributed under the GPL‑2.0 license, making it freely available for modification and redistribution without subscription requirements.

The software targets administrators and organizations that need a lightweight, open‑source solution for providing webmail access to existing IMAP mailboxes. It supports standard email features such as folder navigation, address book, and message filtering, and can be extended with plugins for additional functionality. Compatibility updates are provided for newer PHP versions, including PHP 8, ensuring it can be maintained on current server stacks.

SquirrelMail’s distinguishing aspects are its long‑standing stability, a focus on self‑hosting, and a community‑driven development model that supplies regular security and performance patches. The project includes documentation, plugin support, and a history of releases that address compatibility with evolving PHP environments.