Yes, people who do not use Outlook 2003 or 2007 can use email2, but only through the email2 Web Client.
Even though the email2 Toolbar is only available for Outlook 2003/2007, the email2 Web Client can be used to reproduce all of the the functionality available in the email2 Toolbar.
When you receive an email2 Notification message, it includes a link to access the email2 Web Client. If you current email client is not supported by the email2 Toolbar, you can still access your email2 Message by using the email2 Web Client.
Parallel toolbar development for additional mail clients will begin in future versions. If you are unable to use the email2 Toolbar because your email client is not supported, we invite you to check back often.
// Edited July 2008