Account Creation - Are Custom Domains Blocked?

Hey, folks - I’m having issues setting up an Unreal dev account for my business (which uses it’s own domain. It appears the domain name doesn’t receive the account creation 2FA mail when registering account. I’ve followed all the typical remediation steps (request a new mail, check the spam folder, etc.), but no mail - so I can’t register a new account.

Is this a known issue? How would I go about resolving this, y’all?