You can apply the Do Not Send a Response option easily to accept a meeting request without sending response in Outlook.

1. In the Mail view, click to open the meeting request in the Reading Pane.

2. Go ahead to click Accept > Do Not Send a Response at the top of the Reading Pane.

Now the meeting request is accepted and added to your calendar automatically without sending the meeting response.

Accept declined meeting (meeting you declined) in Outlook

Forward meeting as email without notifying meeting organizer in Outlook

Disable calendar notification in Outlook

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