Administrators can set a Group Policy to disable the Do Not Send a Response option in Outlook 2013 or hide the option in Outlook 2016 when attendees accept a meeting request. This policy disables the third option in the meeting response dialog box and on the shortcut menu in Outlook 2013. In addition, it also disables the option when you delete a meeting request in Outlook 2013. For Outlook 2016, the option is hidden.
To add and set the Group Policy, follow these steps.
Important Follow the steps in this section carefully. Serious problems might occur if you change the registry incorrectly. Before you change it, back up the registry for restoration in case problems occur.
Exit all Microsoft Office applications.
Start Registry Editor:
In Windows 10, go to Start, enter regedit in the Search Windows box, and then select regedit.exe in the search results.
In Windows 8 or Windows 8.1, if you're using a mouse, move it to the upper-right corner, go to Search, enter regedit in the search text box, and then select regedit.exe in the search results.
In Windows 7, go to Start, enter regedit in the Search programs and files text box, and then select regedit.exe in the search results.
Locate and then select the following registry entry: