example.comdomain that is hosted in Plesk is set as SMTP Server in Gmail > Settings > See all settings > Accounts and Import > Send mail as.
- In an attempt to send an email via Gmail the error below is shown:
TLS Negotiation failed, the certificate doesn't match the host
The CN(common name) of the SSL certificate does not match with the mail server name.
Starting from April 2, 2020, the Gmail is verifying that the CN of the SSL certificate is the same as for the mail server.