Earthlink has embarked on a quest to reinvent Web mail for its members. In May, the ISP will launch a beta of EarthLink Enhanced Webmail, powered by Flash-based software from Laszlo, that looks and behaves like a desktop e-mail client.

Earthlink Enhanced Webmail is a single page rich Internet application that eliminates the need to click back and forth between pages, and having to refresh pages between tasks or preference changes. The service will initially be restricted to Earthlink subscribers, but the company has not ruled out opening it up to a wider Internet audience.

BetaNews was shown a live demo of the service -- currently in alpha -- that was in working order and almost feature complete. The Flash interface loads quickly from a file that is approximately 250 KB and comparable to the size of Google's GMail Web-based e-mail.

Earthlink's offering "prefetches" a header list upon log-in to display the most recent inbox messages for immediate scrolling. The header list is limited to 100 messages to spare log-in speed.

New mail can be sorted on the fly by ordering columns and viewed by selecting panes and resizing columns - similar to a standard desktop application. The service checks for new mail without interrupting a user's task. Likewise, e-mail is sent in the background while users perform other tasks.

Users can toggle between the mail folder tab and an address book on the fly. The address book expands panels and collapses trees that contain additional contact information. A drag-and-drop interface element makes it possible to drag a contact into the "To" e-mail field, and to move messages between folders. The software also features inline auto-complete and error messages.

BetaNews tested this feature by purposely leaving the "To" field blank. The resulting error message was displayed underneath the field asking for a correction. The interface also has "tooltip helpers" that provide helpful hints when users scroll over interface items.

Enhanced Webmail will be available as a beta test for Earthlink subscribers in May, providing them with 100MB of storage space. Earthlink has made the service compatible with most mainstream Web browsers and operating systems.

Storage capacity will be increased to 1GB in Q3 or Q4 of 2005, Earthlink says. According to its own estimates, Earthlink currently has 3.5 million Web mail users.