Hi, I have a Exchange 2013 environment, I want if a user schedule a meeting room nobody won't reschedule that room, he get a notification message and exchange deny him for reschedule that room.

T

Hello

Set-CalendarProcessing -AllowConflicts $false not help?

Sorry it did not resolve my problem, same time user can book the meeting room, Exchange don't prevent him, after few times he get a decline mail but my requirement is Exchange server will instant decline him when he make a schedule for a meeting room which was already booked.

Hello

if allowconflict false default decline meeting in same time.
I think user error. user directly open room calendar and create meeting or user create meeting and set "free" the meeting.