title: How to send Outlook tasks requests by mail without Outlook?
body: <p>I need to replicate the <code>Outlook</code> feature/functionnality to send some tasks requests to someone (<a href="http://office.microsoft.com/en-us/outlook-help/assign-a-task-to-someone-else-HP005242813.aspx" rel="nofollow noreferrer">see here</a>) but with mails sent from a webserver using <code>ASP.NET C#</code> and without Outlook installed on the webserver (thus using outlook automation is not possible).</p>
  
  <p>I already check what are the possiblities to do this, and it seems a common way to send tasks to someone is to generate an <code>.ics</code> file in <code>iCalendar</code> format, and include that file to the mail (<a href="https://stackoverflow.com/questions/461889/sending-outlook-meeting-requests-without-outlook">see this stackoverflow question</a>).</p>
  
  <p>It works great, however there is no equivalence of tasks sent by outlook :</p>
  
  <ul>
  <li>Events (VEVENT) have a start date and end date (like a task) but no "completion" field (which make sense since it is an event, not a task).</li>
  <li>Todos (VTODO) have only a due date, no start date or end date <a href="http://en.wikipedia.org/wiki/Microsoft_Outlook#Calendar_compatibility" rel="nofollow noreferrer">and it is not supported by outlook</a>.</li>
  </ul>
  
  <p>I checked myself what Outlook exactly send in a mail containing a task request : It include a <code>winmail.dat</code> file (with <code>content-type:application/ms-tnef</code>) encoded as <code>Base64</code>. Inside that file (which is a binary file) there is a reference to <code>IPM.TaskRequest</code> which seems to be what i need.</p>
  
  <p>I checked the web and found some TNEF parsers, but i need the oposite : <strong>to generate from C# code a TNEF file that would contains a task request</strong>. I would like to know if there is a way to do that. Using a library (free or not) is not an issue.</p>