Yahoo and Gmail desktop notifications appear correctly when the relevant mail domain tabs are open in FF. According to [https://support.mozilla.org/en-US/kb/push-notifications-firefox this page], Firefox can provide on-screen notifications even when the site is not loaded, but in my case this does not work. Is there anything that can be done to receive Yahoo and Gmail mail notifications when the relevant site is not loaded or, as I imagine, this functionality is entirely dependent on Yahoo and Gmail ?