The remote certificate is invalid according to the validation procedure

I am getting this error message

SMTP send error
The remote certificate is invalid according to the validation procedure

while sending test email with SMTPER.

I had my mail account added to Gmail and Outlook for sending/receiving. And it has stopped working.
And today when I ran test on SMTPer, I got above error.
It seems like some issue with SSL certificate.

I would appreciate any help on this matter.
Thanks

Can you please show me the result of //email/testTo: