Post Office – Isle Of Mull, Dervaig – Opening Hours & Branch Details Post Office occupies a prominent space on Dervaig, approximately a 12.62 mile driving distance north-west from the centre of Isle Of Mull (near Kilmore Church). The branch is proud to serve people within the locales of Croig, Sunipol, Calgary, Dervaig, Tostarie, Tobermory and Ballygown. If you’d like to swing by today (Friday), its working times are from 9:00 am – 5:30 pm. Please review the sections on this page about Post Office Isle Of Mull, Dervaig, including the business times, navigation, customer experience and more info.