Hi Daniel,
For investigating email deliverability problems on your site, we have a guide on Troubleshooting Outgoing Email that has recommendations on how you can troubleshoot outgoing email issues that may be present on your site, and explains how email is sent from a Discourse site.
The email logs on your site should show a admin_confirmation_message if the confirmation email had been attempted to have been sent by Discourse. The admin confirmation email should be sending to the address associated with the admin account that you were logged in as when you clicked the “Grant Admin” button.
You may want to check the logs of your email sending provider that you’ve setup your Discourse site to use to see if there are any issues there as well. Any issues with the email not appearing in email provider logs might point to misconfigurations in mail settings or potential email blocking at the service provider level.
If you’re still unable to identify the problem with your email deliverability after going through these steps, you could also consider Creating an admin account from the console, as this will bypass the email verification process.