crond sem enviar e-mail

Alguem sabe como eu faço pro meu cron parar de enviar e-mail, pq (sem brincadeira) em 2 dias ele consegue enviar 400MB (isso mesmo megabytes) pro mail do root, e pra evitar de lotar a hd, eu configurei pra ele enviar pro meu e-mail, ja que assim eu tenho como apagar os e-mails mais facilmente.

O motivo dele enviar tentos e-mails assim, é que eu tive que configura-lo pra executar umas 5 tarefas de 15 em 15 min, e essas tarefas retornam logs gigantescos, se alguem puder me ajudar, eu agradeço.....

root@master:~# cat /var/spool/cron/crontabs/root
# If you don´t want the output of a cron job mailed to you, you have to direct
# any output to /dev/null. We´ll do this here since these jobs should run
# properly on a newly installed system, but if they don´t the average newbie
# might get quite perplexed about getting strange mail every 5 minutes. :^)
#
# Run the hourly, daily, weekly, and monthly cron jobs.
# Jobs that need different timing may be entered into the crontab as before,
# but most really don´t need greater granularity than this. If the exact
# times of the hourly, daily, weekly, and monthly cron jobs do not suit your
# needs, feel free to adjust them.
#
# Run hourly cron jobs at 47 minutes after the hour:
47 * * * * /usr/bin/run-parts /etc/cron.hourly 1> /dev/null
#
# Run daily cron jobs at 4:40 every day:
40 4 * * * /usr/bin/run-parts /etc/cron.daily 1> /dev/null
#
# Run weekly cron jobs at 4:30 on the first day of the week:
30 4 * * 0 /usr/bin/run-parts /etc/cron.weekly 1> /dev/null
#
# Run monthly cron jobs at 4:20 on the first day of the month:
20 4 1 * * /usr/bin/run-parts /etc/cron.monthly 1> /dev/null
root@master:~#

Valeu, ja entendi...foi mal pela ratiada