Comment by achillean

Out of ~6.5 million SMTP servers [1] on the Internet roughly 2.7 million support STARTTLS [2]. However, 1 million of them also support SSLv3 and ~200,000 still allow SSLv2.

[1] https://www.shodan.io/search?query=port%3A25

[2] https://www.shodan.io/report/PIHm43GP