I am experiencing the same problem “certificate not secure....” It appears to be associated with my hotmail.com account being at risk. How do I know what certificate is infected; Shouldn’t malware/internet security have handled the culprit.
I'm wondering how I can get rid of a certificate ... it says Certificate isn't from a trusted authority. If you continue with this certificate your Emails and account may be at risk.
I travelled to Japan and I see issued by mfg02.wifi-cloud.jp
I always choose cancel But the certificate prompt always comes back when I refresh my emails.
Using Samsung email app, Hotmail account.