If you received an email saying, that the certificate validation process for your setup expired, don't worry. This is perfectly normal and actually happens in most cases.
When a setup is created, we automatically start trying to validate, that the DNS records required for the setup have been correctly created. This process will check periodically at increasing intervals for 24-48 hours before stopping. When this happens the setup is put in the 'Certificate validation expired' status (see the upper right corner in the screenshot below) and an email is sent to notify you.
In a lot of cases it takes longer than 24-48 hours to create the DNS records. Maybe you need to get hold of your IT-department, or just need to find the password to log into your DNS provider.
Once the DNS records have been created, you simply need to restart the validation process. First of all, you should make sure, that the records have been created. If you're not creating them yourself, confirm with whoever helped you, that the records have in fact been created.
If you're sure, that the DNS records have already been created before the process timed out, note, that changes to DNS have a so-called 'time to live' (TTL), which is basically an upper limit, to how long it can take for the changes to be available to us (and everyone else for that matter). The validation process may have ended within that period.
Restarting the validation process
Once you're sure, that the DNS records have been created, you can restart the validation process. This can either be done using the link in the email, or by logging in to Cooke Saver and clicking the 'Validate the DNS records' button like shown below.
This will restart the validation process, which may take several hours to complete, but is usually pretty fast.
If you get an error message, like the one shown below, when clicking the button, the required DNS records do not exist, or are incorrect. In this case, you can follow the guide in this article to figure out what's wrong. Once you've corrected any mistakes, come back and click the button again.