Changing sign-in email address - missing confirmation email to new address

I have access to both our old email address domain and the new one. I've received the confirmation email to the old address and confirmed it but the one to the new domain (at O365) hasn't been received nor has the message tracking shown it even coming into Office 365's email system.  I've resent it many times with the same outcome (Einstein's definition of insanity...).  How can this be completed if the new domain email isn't either being sent out by Zoom or is being blocked somehow (with no way to communicate with support either...).