RoundCube makes heavy use of the AJAX-framework and therefore improves the overall performance and usability.
Apart from the existing features the new webmail client offers the following functionalities:
- Multiple sender identities
- Basic address book
- Find-as-you-type address book integration
- Forwarding messages with attachments
- Create or remove custom message folders
- Advanced user interface
- Spell-check
There seems to be an open issue with the opening of large messages through the web. If you face this problem, please use the the alternative webmail-client: http://controlpanel.seantis.ch/tools/webmail