Q1. What is the problem that you are trying to solve?
Is it planned to be able to open a Tls transport (STARTTLS) for email transmission using authentication by client certificate?
Q2 - Who is impacted?
Q3 - Why is it important and/or urgent?
In best practice, using Client Certificate authentication is better than user/password authentication
Q4 - What is your proposed solution? (optional)
Q5. Community support