Acknowledging an Exchange calendar response triggers a new invitation I have Calendar connected to an Exchange 2010 server. I created an event with several (~40) persons. When someone answers I sometimes (not always) have a notification in Calendar with an "OK" button.

If I click "OK" the invitation is sent again to everybody.

I also noticed that sometimes when I snooze an alarm the other invited persons receive a notification per email.

Edit 1

This happens with each and every event that I create on Exchange, not only the example above.

Edit 2

Is there a way to solve the problem?
Or is there a way to gather more information (for example logs)?

Edit 3

I just noticed that when clicking on "OK"



Calendar sends an email to the attendees (I found it in the "Sent" folder) with the invitation attached (which makes no sense).

BEGIN:VCALENDAR
METHOD:REQUEST
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
ORGANIZER;CN=:MAILTO:********
ATTENDEE;ROLE=REQ-PARTICIPANT;PARTSTAT=NEEDS-ACTION;RSVP=TRUE;CN=HÃ¤ubi  J
 Ã¼rg A. (ID PPF):MAILTO:********
DESCRIPTION;LANGUAGE=en-US:When: Thursday\, January 29\, 2015 2:00 PM-3:00 
 PM. (UTC+01:00) Amsterdam\, Berlin\, Bern\, Rome\, Stockholm\, Vienna\nWhe
 re: STB H11.1\n\n*~*~*~*~*~*~*~*~*~*\n\n\nORIGINAL TEXT\n
SUMMARY;LANGUAGE=en-US:Archivmigration
DTSTART;TZID=W. Europe Standard Time:20150129T140000
DTEND;TZID=W. Europe Standard Time:20150129T150000
UID:484366B6-E758-4B66-B590-E42D1797C805
CLASS:PUBLIC
PRIORITY:5
DTSTAMP:20150123T152428Z
TRANSP:OPAQUE
STATUS:CONFIRMED
SEQUENCE:1
LOCATION;LANGUAGE=en-US:STB H11.1
X-MICROSOFT-CDO-APPT-SEQUENCE:1
X-MICROSOFT-CDO-OWNERAPPTID:2112993755
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-DISALLOW-COUNTER:FALSE
BEGIN:VALARM
ACTION:DISPLAY
DESCRIPTION:REMINDER
TRIGGER;RELATED=START:-PT15M
END:VALARM
END:VEVENT
END:VCALENDAR


This does not seem to be generated by Calendar (PRODID:Microsoft Exchange Server 2010), it seems that Calendar sends back the confirmation it received.

Edit 4

I am using Calendar 8.0 on Yosemite but the problem was already present on Mavericks before the upgrade.
This is a problem between Microsoft Exchange and your mac. I have had same issue a while ago, and decided not to change stuff via an Apple device.

I know it's not the answer you were hoping for, but's the reality at this moment.