Login to cPanel and go to the emails section.

1. Spam Filters: Select spam box feature, or make sure this is switched on.
2. Saves spam: This feature will save emails that are above the spam threshold set by the server. Some emails are flagged as spam but they could be legitimate customer emails which you do not want to lose.
3. Access spam folder: Click on your trash,junk folder to check if an email has been sent to junk

Ensure junk is deleted off the server regularly.