https://techcommunity.microsoft.com/discussions/exchange_general/smtpresponse-451-4-4-397-error-comunicating-with-target-host---421-4-2-1-unable-/3989274
SmtpResponse: 451 4.4.397 Error comunicating with target host. - 421 4.2.1 Unable to connect -- |...
Hello I have: Server Work:Windows Server 2008 R2Exchange 2010Server with issue:Windows Server 2016Exchange 2016Domain: Windows Server 2016 I try...