stratuscdn.com untrusted certificate when opening zoho webmail

stratuscdn.com untrusted certificate when opening zoho webmail

Over the last few days I've started getting the following message from my Bitdefender security software whenever I open zoho mail.

"firefox.exe attempted to establish a connection relying on an untrusted certificate to js.stratuscdn.com. We blocked the connection to keep your data safe since untrusted certificates are issued by unrecognized Certificate Authorities."

The operation of the webmail does not seem to be affected, but is this something that needs investigating? It can occur in firefox and chrome browsers.