Poppawid
poppawid is a free, full featured web based email client written in PHP. It is an extension of the now abandoned "popper_mod" project which was an extension of the origional popper. It runs on any server that can run PHP and mySQL. Uses POP and SMTP. Users can have multiple email accounts setup within their account. Has Calendar, Addressbook, Spell check, Folders, and more. Newer features include Multiple attachments, skinning, filters,bug fixes +. Previously known as Popper_mod-wid