We are currently prohibiting users from send out appointments or emails from Dynamics. Therefore, the warning messages from Dynamics stating 'this appointment will be sent to external users' is not applicable to our organization. The message causes much confusion when users are creating their post-dated appointment activities and they receive this message. The users become fearful that the appointment will be sent to the customers.

Being able to 'turn off' or hide this message would be a value-add for the user experience.