Wordnet 3.0
NOUN (1)
1. 
 the system whereby messages are transmitted via the post office; 
- Example: "the mail handles billions of items every day"- Example: "he works for the United States mail service"- Example: "in England they call mail `the post'"[syn: mail, mail service, postal service, post]
WordNet (r) 3.0 (2006):
mail service
    n 1: the system whereby messages are transmitted via the post
         office; "the mail handles billions of items every day"; "he
         works for the United States mail service"; "in England they
         call mail `the post'" [syn: mail, mail service, postal
         service, post]