I have sent ics file as attachment in email. it is showing rsvp buttons and showing like in below attachment for gmail and adding event directly to calendar. 
But same ics file i have sent to yahoo and outlook.live. ics file showing just as attachment but not showing calendar like gmail. in yahoo mail calender section continuously loading like below screen.
Here is my ics file
BEGIN:VCALENDAR
PRODID:-//Google Inc//Google Calendar 70.9054//EN
VERSION:2.0
CALSCALE:GREGORIAN
METHOD:REQUEST
BEGIN:VEVENT
DTSTART:20190612T103000Z
DTEND:20190612T113000Z
DTSTAMP:20190612T101341Z
ORGANIZER;CN=murali.krishna@mydomai.com:mailto:murali.krishna@mydomai.com
UID:29b88vglogjev1r59qjqd0g811@google.com
ATTENDEE;CUTYPE=INDIVIDUAL;ROLE=REQ-PARTICIPANT;PARTSTAT=ACCEPTED;RSVP=TRUE
;CN=murali.krishna@mydomai.com;X-NUM-GUESTS=0:mailto:murali.krishna@mydomai
.com
ATTENDEE;CUTYPE=INDIVIDUAL;ROLE=REQ-PARTICIPANT;PARTSTAT=NEEDS-ACTION;RSVP=
TRUE;CN=muralibobby@mydomai.com;X-NUM-GUESTS=0:mailto:muralibobby@mydomai
.com
ATTENDEE;CUTYPE=INDIVIDUAL;ROLE=REQ-PARTICIPANT;PARTSTAT=NEEDS-ACTION;RSVP=
TRUE;CN=muralibobb@yahoo.com;X-NUM-GUESTS=0:mailto:muralibobb@yah
oo.com
X-MICROSOFT-CDO-OWNERAPPTID:-287760219
CREATED:20190612T101337Z
DESCRIPTION:-::~:~::~:~:~:~:~:~:~:~:~:~:~:~:~:~:~:~:~:~:~:~:~:~:~:~:~:~:~:~
:~:~:~:~:~:~:~:~::~:~::-\nPlease do not edit this section of the descriptio
n.\n\nThis event has a video call.\nJoin: https://meet.google.com/bis-vec-
fgg\n+1 503-908-2281 PIN: 24553883#\n\nView your event at https://www.goog
le.com/calendar/event?action=VIEW&eid=MjliODZ2xvZ2pldjFyNTlxanFkMGc4MTEgb
XVyYWxpYm9iYnkyMDE1QHlhaG9vLmNvbQ&tok=MjYjbXVyYWxpLmtyaXNobmFAbmVvYnJpYy5jb
21hNDFjNzg4OTlmMjJmOWUxY2U0MDE2OWE3OTc0MTM2MTE2YTY3OTky&ctz=Asia%2FKolkata&
hl=en&es=1.\n-::~:~::~:~:~:~:~:~:~:~:~:~:~:~:~:~:~:~:~:~:~:~:~:~:~:~:~:~:~:
~:~:~:~:~:~:~:~:~::~:~::-
LAST-MODIFIED:20190612T101337Z
LOCATION:
SEQUENCE:0
STATUS:CONFIRMED
SUMMARY:MyInvitation
TRANSP:OPAQUE
END:VEVENT
END:VCALENDAR
Please let me know what tags needs to send to show calender with rsvp buttons in yahoo/outlook.
