To dream that the postman gives you a letter, means that you are looking for some answers that havent been answered yet. The postman is also a symbol of someone who is entered your life not such a long time ago.
Dream dictionary: Postman dream meanings
…Dreaming of a postman, denotes that hasty news will more frequently be of a distressing nature than otherwise. See Letter Carrier….
To better understand this dream, read also the interpretations of mailman.
To see a mailman in a dream symbolizes communication with people. Dream of working as a postman suggests that a message verifies your unconscious mind.