Allows you to send a short message to another person. For
    example, when you call someone who is not in, you can leave a
    message to call you back.
    The MAIL command requires two parameters:
    o  The user name of the person to whom the message is to be sent.
       A logical name can be substituted for the user name parameter.
    o  The message, which must be enclosed in quotation marks (" ").
    Format
      MAIL  [node::]username "short message"