Magento: New order email confirmation not being sent

My client’s customers are not receiving order confirmation email. The problem occur after upgrading Magento to 1.9.1.

What do I find after debugging?

The emails are not being sent directly during checkout but instead are being queued. The queue is being processed via Magento cronjob. I do not know since when this changes made.

I log in to cPanel. Magento cronjob has been set up in server. But why the customer is still not receiving oder confirmation email. The answer is… cron command is incorrect.

wget -O /dev/null -q http://www.CLIENT-DOMAIN.com/cron.php

The command above is not recommended. My advice is to execute cron.php directly.

php /home/username/public_html/cron.php > /dev/null 2>&1

Problem solved.