CKMAIL (abbreviated CK) allows you to check for a particular user's
mail and works when you aren't logged in.  For example, the command:

	CKMAIL MRC

will tell you if MRC has any mail.  There are three replies for no
mail, no new (unread) mail, or new mail.  In the last case, it will
report the user name of the sender.

CKMAIL with no argument will ask for a user name if you are not logged
in, or will CKMAIL yourself.  In this latter case, if you have a
CKSUM.DAT file, CKMAIL will also swap to CKSUM after telling you about
your mail.  READ CKSUM for more information about this.

Mail from "SYS" means that the message was delivered by the mailer and
not the MAIL program.  This happens when the message is going to a
protected MSG.MSG mailbox and the sender is not privileged, or for
network mail.  CKMAIL makes no attempt to peek in the mail file for who
actually sent the mail.