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Configure DKIM in Office 365

Step by step guide for admins on how to configure DKIM in Office 365. Configure DKIM using PowerShell, publish DNS CNAME records and verify DKIM is signing message headers

What is DKIM?

Domain Keys Identified Mail (DKIM) is used to encrypt emails and digitally sign message headers using a pair of DKIM keys. The DKIM signature can be used to verify that the email message hasn't been modified. Implementing DKIM improves your email security by protecting messages and allowing mail servers to check that emails were sent by your authorized domain.

1 Check if DKIM is enabled

Microsoft Admin Center

Exchange Admin Center
Protection - DKIM

Status - DKIM not enabled

Office 365 Security & Compliance Center

Threat management - Policy - DKIM

Select domain

DKIM is not enabled

2 Create DKIM Signing Policy using PowerShell

Connect to Exchange online PowerShell

New-DkimSigningConfig -Domain planetexpress.live -Enabled $true 

WARNING: The config was created but can't be enabled because the CNAME records aren't published. Publish the following two CNAME records, and then enable the config by using Set-DkimSigningConfig.

 3 Publish DNS CNAME records




Check the CNAME record has updated with MX toolbox


4 Enable DKIM signing

Once the DNS changes have propagated you will get the option to enable DKIM in the Security & Compliance Admin Center

Threat management - Policy
Select your domain - Sign messages for this domain

Or you can enable DKIM signing using PowerShell

Check the DKIM signing configuration

Get-DkimSigningConfig -Identity planetexpress.live 

Enable DKIM signing

Set-DkimSigningConfig -Identity planetexpress.live -Enabled $true 

DKIM has been enabled

5 Check DKIM configuration

MX Toolbox DKIM Record Lookup

You can use MX toolbox to check your DKIM records


DKIM checks completed OK

Check email message headers

You can verify that DKIM signing is enabled by checking the email message headers

You can also use Google message Header Analyzer to check DKIM

Google Admin Toolbox Messageheader

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