Post Office – Newton Stewart, Sorbie – Opening Hours & Branch Details Post Office is positioned at 16 Main Street, 11.85 miles south from the centre of Newton Stewart (a few minutes walk from Village). The branch is located in a convenient district that primarily serves the people of Monreith, Sorbie, Castlewigg, Garlieston, Mochrum, Whithorn and Portyerrock. Today (Friday), working times start at 9:00 am and continue until 12:30 pm. This page will give you all the information you need on Post Office Newton Stewart, Sorbie, including the business times, address info, telephone number and other beneficial info.