If content approval emails are not sending then chances are system notifications have not been setup correctly. See below for the most common configuration issues.
- The system email address is not set. This is found in the setup window(workarea > settings > configuration > setup).
- The check box below the system email is not checked.
- The user expecting to get email must have workflow and task email enabled in their user settings(workarea > settings > configuration > users > select user > edit). It is disabled by default.