APIM Developer Portal built-in emails

Given that built-in email functionality is currently disabled for Pay-As-You-Go subscriptions, we would like to understand what alternatives are available to enable this feature.

Could you please clarify the following points?

Which Azure subscription types or plans officially support APIM built-in email notifications, including signup confirmation and password reset emails?

Are Azure CSP (Cloud Solution Provider), Microsoft Customer Agreement (MCA), or Enterprise Agreement (EA) subscriptions eligible for this functionality?

What are the associated costs of switching to an eligible subscription? Are there any additional monthly fees or minimum commitments, or would we continue paying based on Azure resource consumption?

Is it possible to convert our existing Pay-As-You-Go subscription to an eligible subscription type without migrating or recreating our current APIM instance?

Is there still a possibility of requesting a backend exclusion for ****DisableEmailsForSubscriptionQuotaTypes, as reported in previous Microsoft Q&A cases, or is this option no longer available?

Our goal is to retain the APIM Managed Developer Portal with native authentication and email notifications while minimizing additional costs and infrastructure changes.

We would appreciate specific information about the eligible subscription plans and their pricing, or guidance on which Microsoft team could provide these details.