Using older versions of Outlook for Mac in business environments
It depends on the Outlook client and what else changed in the meeting.
- If only attendees are added and no other meeting details are changed: Outlook can send the update only to the added attendee(s).
- If other meeting details are changed such as the time/date, subject, or body of the meeting, the update is sent to all attendees.
For legacy Outlook for Mac with the REST calendar sharing feature:
- When attendees are added or removed, updates are sent to changed attendees only.
- When meeting details such as time/date, subject, or body are changed, updates are sent to all attendees.
In Outlook generally, when adding attendees as the meeting owner, there is also an option to choose whether to send updates to:
- Only added/removed attendees, or
- All attendees
References: