From https://proadminz.ru/postfix-otpravka-pochtyi-po-zashhishhennomu-kanalu/

9/18/2016 - 2:57 PM

smtp_tls_security_level = may
smtp_tls_ciphers = export
smtp_tls_protocols = !SSLv2, !SSLv3
smtp_tls_loglevel = 1

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