Sender verification checks are performed on your server for incoming email and these checks help prevent unverified/spam email from arriving at your server. However, sometimes there may be a sender that you must allow email from even if their configuration does not allow for these checks to pass.
Ultimately, the sender will need to address these issues, however, you can temporarily allow their email to come through by enabling the following options in your cPanel & WHM server.
Navigate to the following option in the WHM:
WHM >> Service Configuration >> Exim Configuration Manager
Within this section you will want to search for the following options:
Sender verification bypass IP addresses
Trusted SMTP IP addresses
These options will allow you to enter the IP address of the sender you wish to exclude from these verification checks.
For more details please review our documentation.