Scenario:

with the introduction of ProofPoint Essentials it is common practice that new security procedures will be required. This is true if the adoption of ProofPoint Essentials with Azure Office 365. It is also important to accept any TLS connections from ProofPoint Essentials into your O365 tenant.

Creating an Inbound TLS Connection.

1- Sign-In to the Office 365 Admin portal.

2- Click on Admin menu this will launch Admin Center

3- In the Admin Center click on Show All.

4- Then click on Exchange under the Admin Centers which will launch the Exchange Admin Center.

5- Once in the Exchange Admin Center select Mail Flow - Connectors. 

6- On the Connectors page click Add a Connector to create a new send connector.

7- On the New Connector page select Connection From "Partner Organization" then click Next. 

8- Next provide a name for the connector and turn on the rule and click Next. 

9- Then you will need to add the following IP address to the list of ProofPoint Essentials IP addresses which are allowed to be connected via TLS IP ADDRESSES, the list will depend if you are a client on the US stack or EU stack. You must first select the option BY VERIFYING THAT THE IP ADDRESS OF THE SENDING SERVER MATCHES ONE OF THE FOLLOWING IP ADDRESSES, WHICH BELONG TO YOUR PARTNER ORGANIZATION. You must add each IP address rage in the field provided and click the PLUS "+" sign and click NEXT. 

10- Then click NEXT again to accept the default security settings.

11- On the REVIEW CONNECTIONS page please review your settings and click CREATE CONNECTOR.

12- Click the DONE button to complete the connector.