Gravatar is not getting avatar

Hello,

I tried to use gravatar to get avatars from email services like gmail and outlook (Microsoft) but somehow I managed to get correct url with normilize-url library, but when I open link, photo is blank and like default avatar at facebook profile, but when user registers with custom mail address, picture shows fine. I don`t really understand how gravatar works but there is somehow problem to get picture from bigger services like google and microsoft, is there solution for this problem other then oauth technology of login?