How to activate DKIM in Microsoft 365?

How to activate DKIM in Microsoft 365?

What is DKIM? (DomainKeys Identified Mail)

DKIM (DomainKeys Identified Mail) is an e-mail security standard designed to ensure that messages are not altered in transit between sender and recipient.

So with DKIM you can add a digital signature to outgoing e-mail messages in the message header. When you configure DKIM, you give the domain permission to link its domain name to an e-mail message using cryptographic verification. A kind of signature of your domain, in other words. E-mail systems that receive e-mail from your domain can use this digital signature to determine whether the incoming e-mail is genuine.

How to activate DKIM in Office 365?

Select the domain you wish to configure DKIM on the DKIM page.

Enable DKIM by clicking on the domain.


You will receive this error message if the DKIM activation attempt fails.

The reason why you get this error message is because no DNS settings have been added for DKIM.

CNAME record does not exist for this config. Please publish the following two CNAME records first. Host Name : selector1._domainkey Points to address or value:

Host Name : selector2._domainkey Points to address or value:

If you have already published the CNAME records, sync will take a few minutes to as many as 4 days based on your specific DNS. Return and retry this step later.

Login to the domain portal to adjust DNS settings

As in this blog, where you can configure the primary DNS settings, it is important that the selectors are also placed.

Open the domain-administrators panel where you registered your domain name.
You can copy these 2 DNS records from the DKIM panel above. (See screenshot above, in red)

Add the 2 DNS CNAMES to the control panel with the desired domain and the correct 'tenantname'.

Example from

Example of both DNS CNAME settings.


Activate DKIM after DNS settings

Activate via: -> DKIM again.

DKIM is now activated and can be used for the configured domain.


More information on Microsoft Docs.

Also read

How to use the latest version of Apple Passwords in iCloud for Windows?
Managing app passwords for legacy applications - Multi-factor authentication
How to password protect e-mails in Microsoft 365 or Outlook?



Welcome to On this website you can read articles and experiences about Office 365 with focus on Microsoft Teams. Feel free to ask me a question and I will answer it in a blog post. Help others by giving feedback at the bottom of the articles. This blog is made in Dutch. The multilingual website is offered with best-effort machine translation.
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