Setting up DKIM on custom domain - (dkim=none (message not signed))

Question

Hello,

I am trying to setup the DKIM for our domain. The domain is all setup through exchange and working correctly, however I have enabled DKIM and when I send an email to my Gmail account, it states that the authentication results are that the message is not signed in the message headers.

authentication-results: dkim=none (message not signed) header.d=none;dmarc=none action=none header

I have gone through the Microsoft article and can see this explained where either

• The sender and recipient email addresses are in the same domain.
• The sender and recipient email addresses are in different domains that are controlled by the same organization.

https://learn.microsoft.com/en-us/microsoft-365/security/office-365-security/email-authentication-dkim-configure?view=o365-worldwide#to-confirm-dkim-signing-is-configured-properly-for-microsoft-365

As this is a Microsoft 365 email to Gmail, this doesn't fit in the above criteria.

I have seen online that I need to the run the Enable-OrganizationCustomization command. Is that correct? Just wondered if anyone had any advice on that?

Thanks!

Luke

Answer 1

Hi @Luke,

I tested in my lab but cannot reproduce this issue.

Did you follow these steps in the below link to enable DKIM for your custom domain?

To enable DKIM signing for your custom domain in the Microsoft 365 Defender portal

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