Mail client shows warning connecting to Plesk mail server: the server to which you are connected uses a security certificate that can not be verified. The main destination name is not valid -
![Email server certificate valid according to CheckTLS, invalid according to Thunderbird - Server Fault Email server certificate valid according to CheckTLS, invalid according to Thunderbird - Server Fault](https://i.stack.imgur.com/kndIA.jpg)
Email server certificate valid according to CheckTLS, invalid according to Thunderbird - Server Fault
![Field notes: What is the current default SMTP certificate for your Exchange Server environment? - It works in my tenant Field notes: What is the current default SMTP certificate for your Exchange Server environment? - It works in my tenant](https://dirteam.com/bas/wp-content/uploads/sites/10/2020/06/exchange-2016-assign-ssl-certificate-04.png)