SPECIAL DELIVERY: Mark Perry  will appear as his alter ego, Post Mark the North Pole Postman, at Magic Beans toy shops in Wellesley and Cambridge next weekend to read from his new book, “ ‘Post’ Mark — Santa’s Misfit Postman.”  

The story, which will be published next year,  describes the adventures of a boy who is teased about his desire to travel the world before achieving his dream as Santa’s mailroom helper. At the Magic Beans locations, Perry will also assist children in writing free letters to Santa, with stationery and coloring pages provided.