MTA-STS with TLS Reporting

[dumblob]

🚀 Feature

In the light of current news about Gmail implementing MTA-STS and TLS Reporting, I'm opening this feature request tracking the potentially needed bits to support MTA-STS and TLS Reporting also in the MUA Cypht.

Some more information about MTA-STS e.g. on https://www.hardenize.com/blog/mta-sts and also a validator for MTA-STS. See also APNIC information about TLS Reporting - TLS-RPT.

Design, Layout, Architecture

1. My first request would be to tell the Cypht user whether when sending someone an email would leverage MTA-STS or not (maybe something similar like the validator above?).
2. As in point (1), but for TLS-RPT.

[marclaporte]

Related: https://github.com/jasonmunro/cypht/issues/241