1.MAIL> SET SIGNATURE_FILE BUSINESS_CARD.SIG

      In this example, the user specifies that the file
      BUSINESS_CARD.SIG is to be appended to every mail message sent
      using the FORWARD, MAIL, REPLY, or SEND command.

    2.MAIL> SHOW SIGNATURE_FILE
      Your default signature file is BUSINESS_CARD.SIG.

      This example shows how to use the SHOW SIGNATURE_FILE command
      to determine if a signature file is currently set.