Cert hết hạn làm mail từ 365 về On-prem lỗi
Reason: [{LED=450 4.4.317 Cannot establish session with remote server [Message=451 5.7.3 STARTTLS is required to send mail]
Get-ExchangeCertificate | fl Subject,Issuer,Thumbprint
$cert = Get-ExchangeCertificate -Thumbprint THUMBPRINT_CERT
$tlscertificatename = "<I>$($cert.Issuer)<S>$($cert.Subject)"Set-ReceiveConnector "Default Frontend XXX" -TlsCertificateName $tlscertificatename
Restart-Service MSExchangeFrontEndTransport
Restart-Service MSExchangeTransport
