You can use the added TLS certificate as an active server or client certificate. If you are using TLS encryption, having an active server certificate is optional. An active client certificate is optional even when the client TLS security mode is enabled.
To set a certificate as active:
In the application web interface window, select the Settings → Built-in MTA → TLS Encryption section.
To assign a TLS certificate that will be used for processing inbound SMTP connections as the active server certificate, in the row with the relevant certificate, enable the switch in the Use as server certificate column.
To assign a TLS certificate that will be used for processing outbound SMTP connections as the active client certificate, in the row with the relevant certificate, enable the switch in the Use as client certificate column.
The certificate is made active.
To make the current certificate inactive:
In the application web interface window, select the Settings → Built-in MTA → TLS Encryption section.
If you want to make the currently used server certificate inactive, make a different certificate active using the switch in the Use as server certificate column.
The previously active server certificate is automatically made inactive.
If you want to make the currently used client certificate inactive, in the row of that certificate, disable the toggle switch in the Use as client certificate column.