Problem: Plesk error email “Could not issue/renew Let’s Encrypt certificates for <user>” / contact email has invalid domain

One solution to resolving the Plesk admin error email message with the subject line above and contains the text: “Error validating contact(s) :: contact email has invalid domain: Domain name does not end with a valid public suffix (TLD) “

1. Go to Plesk > Tools & Settings
2. Select SSL/TLS Certificates
3. Scroll down to Keep Plesk Secured
4. Click on the slider control icon and make sure the email address specified in the box isn’t local to the machine, then click update.