.ics email replys from Microsoft Exchange Server not recognized due to missing organizer property

Is your feature request related to a problem? Please describe.

I got a reply to my calendar invite via e-mail including an ics file in Nextcloud Mail. Now Nextcloud says "the invitee accepted your invitation" but it also cannot associate the reply with a Nextcloud user because the ics file doesn't contain an organizer e-mail.

The content of the ics file is:

BEGIN:VCALENDAR
METHOD:REPLY
PRODID:Microsoft Exchange Server 2010
VERSION:2.0
BEGIN:VTIMEZONE
TZID:W. Europe Standard Time
BEGIN:STANDARD
DTSTART:16010101T030000
TZOFFSETFROM:+0200
TZOFFSETTO:+0100
RRULE:FREQ=YEARLY;INTERVAL=1;BYDAY=-1SU;BYMONTH=10
END:STANDARD
BEGIN:DAYLIGHT
DTSTART:16010101T020000
TZOFFSETFROM:+0100
TZOFFSETTO:+0200
RRULE:FREQ=YEARLY;INTERVAL=1;BYDAY=-1SU;BYMONTH=3
END:DAYLIGHT
END:VTIMEZONE
BEGIN:VEVENT
ATTENDEE;PARTSTAT=ACCEPTED;CN=Example Name:mailto:example@foobar.c
 om
UID:46CC0494-EEB2-4EC9-87F5-B71E78573F97
SUMMARY;LANGUAGE=en-GB:Accepted: Event name was here
DTSTART;TZID=W. Europe Standard Time:20260209T103000
DTEND;TZID=W. Europe Standard Time:20260209T110000
CLASS:PUBLIC
PRIORITY:5
DTSTAMP:20260207T105935Z
TRANSP:OPAQUE
STATUS:CONFIRMED
SEQUENCE:2
LOCATION;LANGUAGE=en-GB:https://portal.101lab.it/call/d9jhj7my
X-MICROSOFT-CDO-APPT-SEQUENCE:2
X-MICROSOFT-CDO-OWNERAPPTID:0
X-MICROSOFT-CDO-BUSYSTATUS:BUSY
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-REQUESTEDATTENDANCEMODE:DEFAULT
X-MICROSOFT-ISRESPONSEREQUESTED:FALSE
END:VEVENT
END:VCALENDAR

Describe the solution you'd like

How about we do not care if the organizer e-mail is in the ics file but instead just check if the recipient e-mail address matches the e-mail address registered in my account in Nextcloud?

Describe alternatives you've considered

I also thought about other possibilities to match the replys with the right inviting events:

• Using the UID https://icalendar.org/New-Properties-for-iCalendar-RFC-7986/5-3-uid-property.html
• Using event name and time from the ics and checking if there is a matching event in one of my calendars that has a pending invitation to the sender of the reply e-mail

Additional context

No response

No file or test is identified in the issue. Trace the handling of incoming iCalendar reply messages and how the organizer address is used to associate them with Nextcloud users or events; done means Exchange replies without an organizer email are matched to the appropriate invitation without breaking existing replies.