After email product installation, default TLS certificate information appears in the Settings > Inbound/Outbound > TLS Certificate page, in the TLS Certificate for Incoming Connection section. Details include the certificate version, serial number, issuer, and expiration date.
You can generate a new certificate when that default one expires. On the Settings > Inbound/Outbound > TLS Certificate page, click
Generate to create the new certificate. You should note that generating a new certificate overwrites any certificate that currently exists.