In Outlook for Windows, the standard Accept / Tentative / Decline response options may be unavailable if the organizer added the recipient as a resource instead of as a required/optional attendee, especially when the recipient is external to the organizer’s domain. In that case, the buttons do not show the usual response options and the organizer does not receive a proper response, so tracking and calendar updates do not work as expected.
To restore normal behavior for future invitations, the organizer must:
- Remove the recipient from the meeting as a resource.
- Add the same recipient back as a Required or Optional attendee.
- Send an updated invitation.
Once added as a regular attendee, the invitation will show the usual Accept, Tentative, and Decline options, and responses will update the calendar correctly.
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