Mozilla Thunderbird is a free email client that has many of the features that are offered by Microsoft Outlook Express  but it is free to download.  It is  possible to add extra features in the same way as the Mozilla Firefox browser, but the basics include mail folders, additional viewing windows with message tagging and search facilities. Contacts can  be added, sorted etc and there is an RSS reader plus web based access.

Marco's Accessibility blog has many discussions about the accessibility of Thunderbird  and Mozilla offer volunteers the chance to help with de-bugging and any issues that may arise by joining their Thunderbird testing wiki