This may take up to 24 hours to fully propogate the Microsoft environment, please plan accordingly. 

The following steps begin with logging into https://admin.exchange.microsoft.com with credentials authorized to make enterprise-wide email configuration changes.

• DKIM / DMARC Validation

Create Basic Connector

In the Exchange admin center (https://admin.exchange.microsoft.com/#/connectors), navigate to Mail Flow -> Connectors, and click on “Add a connector”

Configured your connector as a “Partner Organization”:

Name the connector “PhishProtection Inbound”, and optionally add notes:

When prompted, enter ALL of the IPs from ( https://support.duocircle.com/support/solutions/articles/5000524218-ip-addresses-for-firewalls)

Accept the remaining defaults to complete adding the connector:

Upgrade to Enhanced Connector

Once the connector is saved, visit https://security.microsoft.com/skiplisting, to upgrade the connector to an Enhanced Connector. 

Click on the connector, and under “IP addresses to skip”, enter all of the IPs found at https://support.duocircle.com/support/solutions/articles/5000524218-ip-addresses-for-firewalls

Notes

More information about connectors

https://www.undocumented-features.com/2019/08/13/exchange-online-protection-eop-best-practices-and-recommendations/#Enhanced_IP_Filtering_for_Connectors

https://docs.microsoft.com/en-us/Exchange/mail-flow-best-practices/use-connectors-to-configure-mail-flow/enhanced-filtering-for-connectors

https://learn.microsoft.com/en-us/exchange/mail-flow-best-practices/manage-mail-flow-using-third-party-cloud