ircII help: set mail

Usage: SET MAIL [0|1|2]
  When non zero, you will be informed when you have new mail.  This
  is your real unix mail and not irc-mail.  An indicator will light
  up in your status line and a message will be sent to your screen
  telling you about the new mail. If set to 2, the more significant
  headers from the mail are shown.

See Also:
  ON MAIL_REAL
  SET STATUS_MAIL