Hi Eve, Alec, everyone,
I drove the idea of ticket challenge further, to the concept of UMA-compliant communications platform, that does not interfere with the existing email infrastructure.
Interaction with SMTP and IMAP servers is used only if the user has to explicitly demonstrate control of their email address – usually if WebFinger is not available to bootstrap the discovery of claims provider configuration from the email address.
I will use this concept to complete the AEMS project.
Please see the updated sequence diagrams at: https://github.com/uma-email/poc