DKIM Setup - Custom Domain

[SimonInOz]

Hi,

 

Can anyone assist with setting up a custom domain with DKIM? Specifically, I need to know:

 

How are the DNS entries formed, i.e. how should they look, and

 

Do I add entries for the onmicrosoft.com items also when adding my own domain?

 

Want to make sure I do it right..

 

Cheers

[MartinT]

This is a screenshot of our external DNS entry for both DMARC and DKIM (much of it obscured, but you get the idea). If you're creating the DKIM on an Exchange server, I strongly recommend purchasing the DKIM Manager for IIS SMTP and Exchange Server. It makes things a lot easier.

[SimonInOz]

Thanks Martin, I was using this webpage as a reference: https://docs.microsoft.com/en-us/office365/securitycompliance/use-dkim-to-validate-outbound-email#SetUpDKIMO365

 

Is the key generated from the powershell commands?

[HPlum78]

You can use mxtoolbox or dmarcanalyzer.com to help generate dmarc, dkim and spf records. Take a look at they will help unpick the records you need and how they should look.

[MartinT]

Is the key generated from the powershell commands?

 

I used the DKIM Manager to generate the output after selecting the certificate to use (I had to generate a new one today as we have just renewed our certificate).

It also performs a range of tests including full verification after generating an address for you to send a test message to.

[SimonInOz]

Thanks. Also, when I used get-dkimsigningconfig it also shows an entry for Exclaimer, which is our Email signature product. Do I have to enable DKIM for this also? We route email through to them for signature addition.

[MartinT]

I'm not sure as we use Exclaimer in our locally hosted Exchange so there is no re-routing.

[HPlum78]

The way to determine that would be to look at a message header. Would need to see what it's doing to the envelope and the likes. Edited September 26, 2019 by HPlum78

[SimonInOz]

I have it ripped now. This site did it for me: https://o365info.com/enabling-outbound-dkim-signing-verifying-the-process-of-outbound-dkim-signing-in-the-office-365-environment-part-10-10/

 

It steps it all out, and makes it pretty straightforward to implement and test. Includes DNS setup as well, as a bonus.