Fixes

Replacing Send Connector SSL cert Exchange 2016 EMC

Replace SSL Certificate in Send Connector in Exchange Server

$cert = Get-ExchangeCertificate -Thumbprint XXXXXX
$tlscertificatename = "<i>$($cert.Issuer)<s>$($cert.Subject)"

To Replace Send Connector –

Set-SendConnector "Outbound to Office 365" -TlsCertificateName $tlscertificatename

To Replace Receive Connector –

Set-ReceiveConnector "EXCH1\Default Frontend EXCH1" -TlsCertificateName $tlscertificatename

Restart the Exchange Transport service and things should start working.