Horde Groupware Webmail Edition

 Horde Groupware Webmail Edition is a free, enterprise ready, browser based
 communication suite. Users can read, send and organize email messages with
 three different webmail interfaces and manage and share calendars, contacts,
 tasks and notes with the standards compliant components from the Horde
 Project.
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 This package is part of Horde, a web application Framework written in PHP with
 modules like IMP (webmail), Turba (contacts), Kronolith (calendar), Nag (task
 list), Gollem (file manager), etc.