Invalid SSL certificate on Yandex mail

i use mail server of yandex but i get this error when i enter

Welcome to the Cloudflare Community. :logodrop:

Only the operator of the site will be able to fix this. If it is your site, make sure the certificate on the origin server is valid and issued by a recognized public certificate authority. If you are not the site operator you will need to contact them, so they can fix the certificate on their server.