You can set up automatic rejection triggers for when an applicant is applying for a position and meets certain criteria. These triggers will stop an applicant's progress, and if you choose to do so, you can let the applicant see the reason their application was rejected.
To set this feature up, navigate to Configuration > Recruit > Rejection Reasons.
The screen will display all of your rejection reasons that you have entered so far. To add a new rejection reason, click the green "Add a Rejection Reason" button at the top of the screen.
To enable or disable the visibility of each rejection reason, simply check or uncheck the box next to the reason. By default, all reasons will be non-visible to applicants.