For Microsoft Defender for Office 365 and Exchange Online Protection, we are 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.
- Domain pair syntax for spoofed sender entries in the Tenant Allow/Block List
- Microsoft 365 > Manage the Tenant Allow/Block List
Message ID: MC393818
Published: 18 June 2022
Updated: 18 June 2022