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

 Change default port smtp 25 send connector to another port for using Proxmox mail gateway

Set-SendConnector -Identity "connector name" -Port 26

Get-SendConnector "connector name"|fl Port

My domains:

Local domain: vtj-toms.comOutside domain: vtj-toms.com

#NETBIOS name of Client Access exchange server: mail
#Internal FQDN (AD name): mail.vtj-toms.com
#External FQDN (Public name): mail.vtj-toms.com
#Autodiscover name: autodiscover.vtj-toms.com
#SubjectName: cn=mail.vtj-toms.com

Run the following command on the Client Access Server for generating the new Self-Signed SSL cert using the names listed above:

New-ExchangeCertificate -FriendlyName "SelfSigned Cert" -SubjectName "cn=mail.vtj-toms.com" -DomainName mail,vtj-toms.com,mail.vtj-toms.com,autodiscover.vtj-toms.com -PrivateKeyExportable $True