How to delist DNSBL?
This problem we were facing were related to Microsoft Office 365 announcements of disabling the support of TLS older than 1.2 and it has no relation to blacklist or spam. Fixing this issue is by disabling TLS 1.0 AND TLS 1.1 and keep only TLS 1.2
ENABLING TLS 1.2 ON EXCHANGE SERVER 2013 & 2016 – PART 1