How to Configure Self-signed Certificate on Email Security Device.
Login into the ES appliance as admin
On firmware versions 9.0.x and older, go to System Setup > Certificates > Generate/Import
On firmware versions 9.1.x and newer, go to the Manage page, then System Setup > Certificates > Generate/Import
Select “Generate a self-signed SSL certificate" and name the certificate.
TIP: For future administration, include the certificate expiration date in the name
Fill in the hostname and create a passphrase for private key
CAUTION: Passphrase cannot contain any special characters, it must be letters and numbers only
Click on Generate/ Import
Go to Certificates > Configure
Select the certificate for HTTPS/ TLS ( SMTP) radio button and click Apply to save changes