"In addition to LOGNAME, HOME, and SHELL, cron(8) will look
at MAILTO if it has any reason to send mail as a result of
running commands in ``this'' crontab. If MAILTO is
defined (and non-empty), mail is sent to the user so
named. If MAILTO is defined but empty (MAILTO="" ), no
mail will be sent. Otherwise mail is sent to the owner of
the crontab."