Your support now seems to require that requests come from registered email addresses. This system ignores, that people might use various incoming and outgoing email addresses and therefore might not be able to even fulfil that request.
I set up a new forwarding email address for every service I register with, and my IPS email is set up the same way. But I cannot write from that or any of the hundreds of emails I have set up this way, since they are only forwarding addresses. So If you have that requirement, you should let us set up alternative email addresses to contact support and still be clearly identifiable.
I understand that you already have a “alternative contact” function, but that is for a different person. I would only need an alternative email address for the same account.