man 5 crontab
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.
P.S. Занесите в FAQ в 5-ый раз уже спрашивают