It doesnt appear to be phishing email as the link points me directly to my already logged in firefox account. Under connected services I see "Unknown" that I'm not able to sign out of. This seems concerning, and it appears im not alone https://www.reddit.com/r/firefox/comments/1hprwm7/unknown_signed_into_my_mozilla_account/ https://www.reddit.com/r/firefox/comments/1hp058j/erroneous_login_at_4am_from_unknown_device_that_i/ https://www.reddit.com/r/firefox/comments/1hkm8vz/am_i_fucked/ Here are some examples of other users with similar issues