how to disable Cron job mails for all accounts ?

Hi . i have a SPAM problem on port 25 . so i see Mail Queue that is full of spam cronjob mails . how i can disable mail notification for all accounts on cpanel ? i add "/dev/null 2>&1" in at the end of cronjob. 0 1 5 10 * /path/to/script.sh >/dev/null 2>&1
but it is for single account and i need to do it user by user . i'm looking for a single command or a way to disable cronjob notification mails in 1 step for all cpanel accounts . Thanks - Hossein .