DOES NOT WORK with quantum. Takes you to a link to "refresh Firefox" which will REMOVE EVERYTHING from FF: settings, bookmarks, etc.... Tried this in chrome and had similar problems. STAY AWAY!

I love this extension but this just refuses to work on Firefox. Works great on Chrome.

All the help materials by this author are for Chrome.

Для хрома отличное расширение, но на ff57 даже не запускается. Fail. Fix it! https://goo.gl/xA2ZyQ

Just display « Display images Always display images Stop undo »

До обновления было ЛУЧШЕЕ дополнение! После обновления - стало хуже некуда!
В течение получаса ЗАБЫВАЕТ все ящики и пароли к ним! Надо каждый раз вводить всё заново! Отстой!
Автор, Верните предыдущую версию!

Worked at first, but now it never remembers multiple accounts, only recognises two of my three accounts, and opens one of my accounts as another account. Tried all the fixes suggested in troubleshooting and none work, problem is persistent. Very frustrating.

Pues eso, después de instalar este complemento, y teniendo la sesión en Gmail abierta, me pide iniciar sesión en Gmail; y después de hacerlo no ocurre nada, dado que me sigue pidiendo iniciar sesión. He desinstalado el complemento porque además no me convence el tamaño que ocupa...

it looks modern with good features, but it's not what it seams to be.
Auto login always fails.
Manually account is "forgotten" several times, very often asks for login and permission - again and again.
it looks like it does not actualize very often, i have to do it manually.
The configuration is not actualized for FIREFOX users.
Help and config only for Chrome.
simply doesn't do for what it's builded for, at least NOT in Firefox, and it's laggy very often, sometimes fast.
I cannot recommend it anymore after using it 2 Weeks.

Many thanks to author. I moved on from GMailChecker https://addons.mozilla.org/en-US/firefox/addon/gmail-checker/ and want to say that CheckerPlus is a gorgeous and stunning add-on.

Esta misma extensión en Chrome es muy buena, de las mejores, pero en Firefox se notan las carencias del programador en este entorno porque es una extensión muy pobre.