M365 Changelog: Add DKIM Domain in Sending Infrastructure for Tenant Allow Block Lists-Spoofing

MC393818 – For Microsoft Defender for Office 365 and Exchange Online Protection, Microsoft is adding support for providing “DKIM verified domain” as the “Sending Infrastructure” within Tenant allow-block lists-Spoofing, so that Security Administrators can better manage Anti-Spoofing activity and override it based on Spoof Intelligence. Currently, what is supported in this field is either the domain from DNS PTR record or /24 IP Subnet. Additionally, being able to specify a ‘DKIM verified domain’ will help serve scenarios where shared infrastructure provider services are used for sending emails. Since the DKIM domain is unique to each tenant and if it passes verification even when other authentication signals fail, if desired for legitimate business reasons, a spoofed message can still be allowed instead of being blocked.

This message is associated with Microsoft 365 Roadmap ID 93359

When this will happen:

Standard: Rollout will begin in early July and is expected to be completed by late August.

Gov Cloud: Rollout will begin in early September and is expected to be completed by late September.

How this will affect your organization:

Once this change is completed, Security Administrators will be able to specify a verified DKIM domain within the Sending Infrastructure field using Tenant allow block lists-Spoofing in order to allow/block a spoofed domain pair using DKIM domain. 

What you need to do to prepare:

There is nothing you need to do to prepare for this change. You may want to notify your users about this change and update your training and documentation as appropriate. 

Additional information