This has nothing to do with the problems with the outgoing mail.
PHP mail() on cron fails in a different way and was a problem before the current general problem with mail().
They turned off the email notification by the cron daemon a long time ago. It was putting too much strain on the mail server. You have to catch errors on your own.
Add something like:
Code:
>>/home/cPanelUserName/public_html/cron_log.txt 2>&1
to the end of your cron command. That way any output, even system errors will be logged. Add an echo that outputs the time and you will be able to see if the cron is running or when it ran last.