Continuous reinstallations of SSL in mail server


I have a question.

Today I have at least 5 certificate reinstallations on the mail server

Every time I want to send emails I get the message that it cannot connect to the tcp server

It didn’t happen to me before, will there be a problem with the certificate generator?

If so, how can I add another valid certificate to the server and I don’t know if it is the same one that I can issue on the zero ssl page or because it is for a mail server it must be different!

Thank you for your attention