The Collaborative International Dictionary of English v.0.48:

mail carrier \mail carrier\ n.
   A person who delivers the mail; -- also called a letter
   carrier. A male mail carrier is also called a mailman.

   Syn: postman, letter carrier, carrier, mailman.
        [WordNet 1.5 +PJC]

WordNet (r) 3.0 (2006):

mail carrier
    n 1: a man who delivers the mail [syn: mailman, postman,
         mail carrier, letter carrier, carrier]