The error type "The remote server's SSL certificate or SSH fingerprint was rejected" occurs when the SSL certificate is being used on the main domain and not Sub-domains.
- Check the URL in Admin > Webhooks
- Click on the webhook in the right corner.
- For example, if the URL is, https://onlineservices.test.marketo.com, the certificate needs to be valid on *.test.marketo.com and not just *.Marketo.com.
- Check this by verifying the certificate on "https://www.sslshopper.com" and all the certificates will be listed as Subject Alternative Name's if the certificate is valid on the sub-domains.
For Google.com "https://www.sslshopper.com/ssl-checker.html#hostname=google.com", the certificate is valid on *.Google.com as well as all the subdomains as listed in SAN's.