where are all the shadow mailboxes?
['In the northern section of Lazy Lake.', 'The eastern side of Misty Meadows.', 'The east end of Slurpy Swamp.', 'The northwestern portion of Holly Hedges.', 'The west side of Sweaty Sands.', 'The northwest corner of Pleasant Park.', 'The northwest/central area of Steamy Stacks.']