One of our support engineers (not me, so let’s give credit where credit is due) wrote a script to help you, as a customer of Office 365, validate for DKIM configuration once you have enabled it in the Admin Portal. We’ve added a few more checks to make it more clear, but you can also use this.
To verify your DKIM configuration:
1. Copy/paste the below script into a file, Validate-DkimConfig.ps1
2. Connect to Exchange Online using Powershell, making sure that the directory you are in is the same as where you saved the script above.
3. Type the following command in Powershell:
4. To check the config for a single domain, run the following command:
To show the full signing config, use the –showAll switch:
Validate-DkimConfig <domain> –showAll
To validate all domains for your organization, run the following command:
You will be able to see if anything is wrong because the output is color coded.
Update on May 12, 2016 - This script now lives on GitHub (instead of you having to copy/paste it here), and it fixes some key/dns missing errors https://github.com/carlnolan/scripting/blob/master/Validate-DkimConfig.ps1
Thanks to Carl Nolan for putting this up.