Roundcube Webmail is a browser-based multilingual IMAP client with an app-like user interface. It provides full functionality you expect from an email client, including MIME support, address book, folder manipulation, message searching and spell checking.

Key Features Include:

• Multilingual capabilities.
• Find-as-you-type address book.
• Richtext/HTML message composing.
• Searching messages and contacts.
• Canned response templatesNew.
• Int. domain names (IDNA).
• Shared folders and ACL.
• Full featured address book.
• Extensible using the Plug-in API.

Roundcube Webmail is free (in terms of license and cost), so that means it could be an ideal solution for SMBs who wants to offer webmail to its members either as a primary or secondary service.