The program that changes the local of the delivery for surepost package is based on forecasted packages for any giving day if it forecasted that there are multiple packages going to a address either multiple surepost or a combination or surepost and no surepost UPS will make the delivery. That being said all forecasted package don't always make it to the building on the day forecasted so some days you have only one surepost package that was suppose to be delivered to the Post office but instead is being delivered by UPS.