Unable to delete appointment using the ical file i

Question

We have the following requirement.

1) We need to generate an appointment with recurrence pattern, and send it to attendees. 2) Later we need to update, delete single occurrence out of the recurrence pattern. 3) We may also need to delete the complete the recurrent appointment in some cases.

By delete, we mean the meeting should be marked as cancelled in the invitee's calendar.

We are sending the appointments via our web app sending an email to the attendees with .ICS file embedded in email. We are generating the email using Java Mail API and embedding the .ICS file as multipart message keeping the MIME type as text/calendar.

Our invitees are using Microsoft outlook Desktop Client, Office 365 Web client, gmail.

We are able to send the appointment with recurrence pattern, and also able to update the specific occurrence of the meeting.

However we are facing difficulty with deleting the appointment or individual meeting specifically in the Outlook Desktop Client. When we send the delete event, in the invitee's mail box, it shows the button as "Remove from calendar" but doesn't mark the meeting as "cancelled" in the user calendar. The same is happening correctly in the Gmail web app.

I have tested it on the Outlook Version shown below

Office 365 MSO(16.0.11601.20184) 64 bit

I also tested a simple test case of creating a simple meeting using the below create.ics file(sending it as part of the mail) and then trying to delete the meeting using the delete.ics file below.

//create.ics
BEGIN:VCALENDAR
METHOD:REQUEST
PRODID:Microsoft Exchange Server 2010
VERSION:2.0
BEGIN:VTIMEZONE
TZID:India Standard Time
BEGIN:STANDARD
DTSTART:16010101T000000
TZOFFSETFROM:+0530
TZOFFSETTO:+0530
END:STANDARD
BEGIN:DAYLIGHT
DTSTART:16010101T000000
TZOFFSETFROM:+0530
TZOFFSETTO:+0530
END:DAYLIGHT
END:VTIMEZONE
BEGIN:VEVENT
ORGANIZER;CN=Test Sirion:MAILTO:[e-mail]
ATTENDEE;ROLE=REQ-PARTICIPANT;PARTSTAT=NEEDS-ACTION;RSVP=TRUE;CN=Kapil Gupta:MAILTO:[e-mail]
DESCRIPTION;LANGUAGE=en-US:\n
UID:040000008200E00074C5B7101A82E00800000000908EB51F4E28D501000000000000000
 01000000000ED265B41C38B479A5315D1D23383D4
SUMMARY;LANGUAGE=en-US:New Meeting
DTSTART;TZID=India Standard Time:20190622T080000
DTEND;TZID=India Standard Time:20190622T083000
CLASS:PUBLIC
PRIORITY:5
DTSTAMP:20190621T105648Z
TRANSP:OPAQUE
STATUS:CONFIRMED
SEQUENCE:0
LOCATION;LANGUAGE=en-US:
X-MICROSOFT-CDO-APPT-SEQUENCE:0
X-MICROSOFT-CDO-OWNERAPPTID:-2091554845
X-MICROSOFT-CDO-BUSYSTATUS:TENTATIVE
X-MICROSOFT-CDO-INTENDEDSTATUS:BUSY
X-MICROSOFT-CDO-ALLDAYEVENT:FALSE
X-MICROSOFT-CDO-IMPORTANCE:1
X-MICROSOFT-CDO-INSTTYPE:0
X-MICROSOFT-DONOTFORWARDMEETING:FALSE
X-MICROSOFT-DISALLOW-COUNTER:FALSE
X-MICROSOFT-LOCATIONS:[]
BEGIN:VALARM
DESCRIPTION:REMINDER
TRIGGER;RELATED=START:-PT15M
ACTION:DISPLAY
END:VALARM
END:VEVENT
END:VCALENDAR


//delete.ics
BEGIN:VCALENDAR
METHOD:CANCEL
PRODID:Microsoft Exchange Server 2010
VERSION:2.0
BEGIN:VTIMEZONE
TZID:India Standard Time
BEGIN:STANDARD
DTSTART:16010101T000000
TZOFFSETFROM:+0530
TZOFFSETTO:+0530
END:STANDARD
BEGIN:DAYLIGHT
DTSTART:16010101T000000
TZOFFSETFROM:+0530
TZOFFSETTO:+0530
END:DAYLIGHT
END:VTIMEZONE
BEGIN:VEVENT
ORGANIZER;CN=Test Sirion:MAILTO:[e-mail]
ATTENDEE;ROLE=REQ-PARTICIPANT;PARTSTAT=NEEDS-ACTION;RSVP=TRUE;CN=Kapil Gupta:MAILTO:[e-mail]
DESCRIPTION;LANGUAGE=en-US:\n
UID:040000008200E00074C5B7101A82E00800000000908EB51F4E28D501000000000000000
 01000000000ED265B41C38B479A5315D1D23383D4
SUMMARY;LANGUAGE=en-US:Canceled: New Meeting
DTSTART;TZID=India Standard Time:20190622T080000
DTEND;TZID=India Standard Time:20190622T083000
CLASS:PUBLIC
PRIORITY:1
DTSTAMP:20190621T110026Z
TRANSP:TRANSPARENT
STATUS:CANCELLED
SEQUENCE:1
LOCATION;LANGUAGE=en-US:
X-MICROSOFT-CDO-APPT-SEQUENCE:1
X-MICROSOFT-CDO-OWNERAPPTID:-2091554845
X-MICROSOFT-CDO-BUSYSTATUS:FREE
X-MICROSOFT-CDO-INTENDEDSTATUS:FREE
X-MICROSOFT-CDO-ALLDAYEVENT:FALSE
X-MICROSOFT-CDO-IMPORTANCE:2
X-MICROSOFT-CDO-INSTTYPE:0
X-MICROSOFT-DONOTFORWARDMEETING:FALSE
X-MICROSOFT-DISALLOW-COUNTER:FALSE
END:VEVENT
END:VCALENDAR

Please let us know if there is any issue with the delete.ics file.

I have also put the code which we are using to send the mail in the below github gist, in case it is relevant.

https://gist.github.com/kapilgupta101292/92769d3e9f8e6444cb9dde5960473b1e

I have already tested by adding the X-WR-RELCALID as suggested in the following Stack overflow link but that doesn't work either -

Delete calendar event using iCalendar file import (Outlook 2003 problem)?

Please review the above ics file and let us know how to achieve the delete of the appointment. Please let us know if any input is required, we need to quickly resolve this issue to deliver our webapp.