Per Thorsheim@dalias There still exist mailservers out there supporting SSLv3, and while BCP 195 from 2021 deprecates the use of TLS 1.0/1.1, they are still very much in use on mailservers, in combination with weak cipher suites.
So I wouldn't be so sure about harvest now decrypt later not succeeding.
The Google transparency report on email also shows that even some BIG mail domains doesn't even do STARTTLS today. I did some work on this in 2014-2015 to make "everyone" use it. :)
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