You can't send a response to a meeting request in Outlook

Original KB number:   3185258

Symptoms

When you try to send a response to a meeting request in Microsoft Outlook, the option is not available. The Accept, Tentative, and Decline buttons do not triggers the expected drop-down options of Edit the response before sending, Send the response now, and Do not send a response.

Screenshot of the Accept, Tentative, and Decline buttons on the Meeting ribbon in Outlook.

Because you can't send a response, the meeting organizer doesn't receive one from you, and the meeting tracking feature is not updated as expected.

Cause

This issue occurs if the meeting organizer added you as a resource to the meeting and you are external to the meeting organizers domain.

Resolution

To work around this behavior, ask the meeting organizer to add you as a required or optional attendee instead of as a resource.