Climbing fig vine. If you want something to stick to a post, try fig vine. The fine, heart-shaped foliage will cling tightly to the post and does best in partial shade. The evergreen vine is susceptible to cold damage when the temperature drops below 10 degrees. Morning glory is a fast-growing annual vine that can overtake a mailbox.
Morning glory likes a warm sunning spot and can handle some drought.
Blue pea vine is an annual that isn't as aggressive and is more suited to a lamp post. Confederate jasmine can grow to 30 feet with white flowers that smell great in the spring. It works best in partial shade, with moist, well drained soil. Lady Banks rose can be a pretty vigorous grower for a mailbox. It has long slender canes with scented pale yellow flowers each spring.