Email is encrypted but the host is not verified

Hello,
I am able to send/receive email from my domain accounts but when I am checking my domain statistic at: //email/testTo:
Then I got an error:
Cert VALIDATION ERROR(S): self signed certificate
So email is encrypted but the recipient domain is not verified
Cert Hostname DOES NOT VERIFY (mydomainname.com != www.example.com)
So email is encrypted but the host is not verified

How can I fix it?

Regards,

I have the same issue