Dynamic meeting response option
When sending a meeting invite to more than 20 people, Outlook should automatically turn off Request Responses / Allow New Time Proposals (in Response Options).
Tally Gonzalez commented
In addition to Accept, Tentative and Decline, could you add an option for "Decline but leave on calendar." A lot of times, meetings are declined due to travel schedules or more important conflicts. However, if the conflict goes away, the person may still want to attend the previously declined meeting