1. Launch Exchange Management Shell
Click on Start and then expand "Microsoft Exchange Server 2019" and right click on Exchange Management Shell and runas administrator.
2. Enter in command
Type in the following command: Get-ExchangeCertificate -Server EX2019A and press enter.
3. Enable Services on certificate
Once you have located the SSL certificate, you can run the following command: Enable-ExchangeCertificate -Server EX2019A -Thumbprint <> -Services IIS,SMTP,POP,IMAP and press enter.