A few months ago I was complaining about the lack of MTA-STS adaptation with major email service providers besides Google. Recently though, I’ve noticed a new player connecting to mta-sts.paranoidpenguin.net to retrieve my MTA-STS policy.

I was not planning to add support for MTA-STS for my domain as I’ve previously deployed DANE for SMTP transport security. MTA-STS is an alternative solution that does not require DNSSEC for authentication but instead relies on certification authorities.