Steps for customers using ProofPoint Essentials:
Expand the Security Settings tab; Click on Sender Lists.
Add the following IP to the Safe Sender List:
159.183.82.50
Click Save.
Steps for customers using ProofPoint Hosted:
Click Email Protection.
Under the Spam Detection drop-down, select Organizational Safe List.
Click Add.
In the Proofpoint - Global Safe List window, enter the following information:
Filter Type: From the drop-down menu, select Sender Hostname.
Operator: From the drop-down menu, select Equals.
Value: In the field, enter the following IP addresse:
159.183.82.50
Click Save Changes.