Cannot receive or use validate email feature

I am trying to validate emails to use with the relatively new
“Email Routing” service. I cannot seem to receive these no matter how many times I click resend, and of course I can send emails from other domains to the email account, so I know that the account exists and is accessible on my end.

How can I get this out of “pending validation” status? I would be willing to do some other alternate method, showing I own and control the domain, such as DNS records, or sending an email from the email address, etc.?

Yes - I have checked incoming Spam folders and there is nothing there, and it is possible that something like grey-listing / tarpitting is going on upstream of me, but there is not much I can do to get that out of the way, if the platform does not try to re-deliver email if it is unable to deliver on the first attempt…