Hello @Mike Lundahl ,
I Understand that you have noticed that it's actually the email your connecting with the user and not with the support mail.
Additionally, you can go through to these documents Email Address Custom Domain , Change Users Email Address to change the email address to the user accounts
Let me know you have additional queries. Happy to assist you further.
I hope the discussion is helpful you can do click Accept Answer
so that it can be beneficial for the community members if you have any further query do let us know.