title: Ical not supported calendar message
body: <p>In hotmail i've the following icalendar that not accepted by hotmail, what is the reason?
  Error: Not supported calendar message:</p>
  
  <p>BEGIN:VCALENDAR</p>
  
  <p>PRODID:-//EcosAgile//V1//EN</p>
  
  <p>VERSION:2.0</p>
  
  <p>METHOD:REQUEST</p>
  
  <p>BEGIN:VTIMEZONE</p>
  
  <p>TZID:W. Europe Standard Time</p>
  
  <p>BEGIN:STANDARD</p>
  
  <p>DTSTART:16010101T030000</p>
  
  <p>TZOFFSETFROM:+0200</p>
  
  <p>TZOFFSETTO:+0100</p>
  
  <p>RRULE:FREQ=YEARLY;INTERVAL=1;BYDAY=-1SU;BYMONTH=10</p>
  
  <p>END:STANDARD</p>
  
  <p>BEGIN:DAYLIGHT</p>
  
  <p>DTSTART:16010101T020000</p>
  
  <p>TZOFFSETFROM:+0100</p>
  
  <p>TZOFFSETTO:+0200</p>
  
  <p>RRULE:FREQ=YEARLY;INTERVAL=1;BYDAY=-1SU;BYMONTH=3</p>
  
  <p>END:DAYLIGHT</p>
  
  <p>END:VTIMEZONE</p>
  
  <p>BEGIN:VEVENT</p>
  
  <p>UID:96d3845d-4cc4-4498-bb4d-7a8503b597e6</p>
  
  <p>SUMMARY:Approvazione richiesta Smart working Tomi, Ivio per il 15/09/2017 Buongiorno Tomi, Ivio
  le confermiamo che &egrave; stata approvata la seguente richiesta:
  Codice Richiesta: 151</p>
  
  <p>Causale: Smart working</p>
  
  <p>Data/Ora Inizio: 15/09/2017 - 18:00</p>
  
  <p>Data/Ora Fine: 15/09/2017 - 20:00</p>
  
  <p>LOCATION:</p>
  
  <p>CLASS:BUSY</p>
  
  <p>CATEGORIES:general</p>
  
  <p>CREATED:20170929T143600Z</p>
  
  <p>DTSTAMP:20170929T143600Z</p>
  
  <p>LAST-MODIFIED:20170929T143600Z</p>
  
  <p>X-XM-SHARE:0</p>
  
  <p>DTSTART;TZID=W. Europe Standard Time:20170915T160000Z</p>
  
  <p>DTEND;TZID=W. Europe Standard Time:20170915T180000Z</p>
  
  <p>SEQUENCE:0</p>
  
  <p>ATTENDEE;RSVP=FALSE:MAILTO:valta@agile.com</p>
  
  <p>ORGANIZER:MAILTO:AgileNotifiche@agile.com</p>
  
  <p>END:VEVENT</p>
  
  <p>END:VCALENDAR</p>