Mozilla Thunderbird is a stand-alone mail client (i.e. no browser+mail client combo) that is intended on users who want to stick with their browsers (such as IE), but want a new mail client to replace the default (such as Outlook Express), and to take advantage of all the extra add ons and benefits that it has to offer.
Homepage:
http : //www . mozilla-europe . org/en/products/thunderbird/
