Ah, not there. Go to Delivery Servers > Update delivery server and you will find "Hourly quota" field. Input "500" there as shown in attachment.
You need to have pcntl extension (php'x'-pcntl) installed and enabled to activate pcntl functionality in MW. But quota settings were not properly applying when pcntl was enabled on older versions of MW, not sure if this is fixed in 1.3.6.2