Roundcube Webmail is a light-footed, mobile-friendly AJAX webmail client with a gorgeous modern interface. If you only require regular email capabilities, and prefer speed over features, then our Roundcube webmail client should do the trick nicely. Give it a try.
Zimbra Collaboration Suite
The Zimbra Collaboration Suite is an enterprise-grade groupware platform, providing shared calendaring, file sharing and email in one interface. Great for teams, or for those wanting the extra features similar to those found in Microsoft Outlook.