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In reply to Comment by Reader Charles

Reader Jarek on 2014-08-13 at 13:30:

One question: how can a client protect itself against a TLS downgrade attack? How can it tell the difference between an SMTP server that has TLS but with a man in the middle and an SMTP server with no TLS?

Using DANE records in DNSSEC. It's quite recent thing, and DNSSEC still isn't such widely deployed, but it's supported by both Postfix and Exim SMTP servers (I think it's disabled by default, though).


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