E-mail is the de-facto standard for office communication in the 21st century. E-mail is exchanged among knowledge workers using e-mail clients like Microsoft Outlook, Mozilla Thunderbird or Novell Evolution and e-mail servers in the backend that store and send the mails.

Applications like mailing lists build upon the wide distribution of e-mail infrastructure and even some online forums like Mindquarry Talk integrate e-mail and act accordingly as mailing list server and mailing list archive.

Most of the daily workflows of knowledge workers center around e-mails. The e-mail inbox has been called "the knowledge workers production line" and the capability to send files as e-mail attachments makes e-mail the most popular file sharing system.

However, with the wide use of e-mail comes a row of problems like SPAM, e-mail overload and the inability to structure e-mail-based file sharing and task assignemts, which lead to the introduction of tools for file sharing and shared todo lists.