SquirrelMail

SquirrelMail is a lightweight, standards-based webmail application that provides a browser interface to existing email accounts. It connects to mail servers using IMAP for mailbox access and typically uses SMTP for sending, making it suitable for many traditional email server setups.

Key Features

• IMAP webmail interface for reading and managing folders and messages
• SMTP support for sending mail (commonly combined with SMTP authentication via plugins)
• Extensible plugin system with a large ecosystem (e.g., spam filtering helpers, authentication options, compose enhancements)
• Address book and user preferences storage (file-based or database-backed depending on configuration)
• Emphasis on compatibility and low resource usage with a simple, HTML-based UI

Use Cases

• Provide web access to mailboxes on an existing IMAP server for users without desktop clients
• Add a lightweight webmail option to self-managed mail servers (e.g., Postfix plus Dovecot)
• Deploy a minimal, plugin-extendable webmail interface for intranets or legacy environments

Limitations and Considerations

• The interface is intentionally minimal and may lack modern “groupware” features found in newer webmail suites
• Ongoing compatibility can depend on using appropriate versions/snapshots for newer PHP releases

SquirrelMail remains a practical choice when you need a straightforward, resource-efficient webmail front end that integrates with standard IMAP/SMTP infrastructure and can be customized through plugins.