This addon is not even open source. Author can see all your email and contents in it. Look at his homepage and privacy policy. At least he is being honest about it.
It is upto you, users to trust this random man on the Internet with your gmail contents. I don't know why Mozilla has this under "Recommended" section.

First too get notified for all that website its okay with us

How do people trust their data to a random guy's extension instead of googles relatively solid service never ceases to amaze me.

This is quite a good app, except I keep seeing a green dot under the envelope icon in the toolbar ...

I click on the dot and it goes away. Then as soon as I open a new tab, or even if I refresh the current tab, the green dot comes back again.

This green dot appears even though there are no emails in my Inbox - it says 'Permission needed' - yet the app has all the necessary permissions in both Gmail, and also defined under my Google Account.

Emails still yet notified anyway, which is great, but the green dot is unrelenting, and comes back all the time.

The only time the green dot isn't there is when I first open my browser - but as soon as I click on anything, ** K-BOOM! ** - yep, there's that darned green dot again.

Very very annoying!

"Checker Plus for Gmail" has gone from excellent to completely useless overnight! This extension worked well until a few weeks ago when the wheels came off:

I can no longer add gmail accounts! I have 3 accounts. There is a very weird "option" in the "Preferences" tab: "AUTO DETECT" or "ADD ACCOUNTS". I never had trouble with this in the past, but now if I select "AUTO DETECT" I cannot add an account, and if I select "ADD ACCOUNTS" I get an error message from "Checker Plus" when I try to add!

No idea what's causing this, but "Checker Plus" has now been relegated to the ranks of "NOT READY FOR PRIME TIME".

Best extension

I don't like to complain about a free tool but the border radius and information density of the new "modern" look are quite bad.

UI goes so ugly with the latest update

Themes

Genuinely this is a mandatory addon for me. I use it so often I actually paid for a free extension, dude earned it.

it works fine but i almost threw up when i saw the ui change please for the love of god stop making everything circular first youtube now this. let me change it back at least it's so ugly