I use this addon for some time now. I use it for my gmail account and my fastmail account. However, since version 4 the fastmail script doesn't work anymore, even it was made by the dev itself. That's no option for me, so i stick to 3.5.23 But the problem in the old version is that gmail doesn't open and instead you're directed to your google account where you have to login. So i now use 3.5.23 for fastmail alone. If the newer version would improve and that i'm able to use both accounts again (gmail and fastmail) i would give it a higher rating.

Multiple logins to Hotmail account may fail and fail.
If you want to check the mail of account A, but the mail screen of account B opens or if you try to open the mail screen of account B with the mail screen of account A open, the screen of account A is reloaded Or it is unresponsive.
It will be helpful if you can rectify it as soon as possible.

Also, do not you ask me to stop checking my email as soon as I launch the browser? I like to check it myself as before

GMail not working on Firefox 53.0.2
I can't install this version (4.0.3). Corrupt addon notification.

GMail not working on Firefox 53.0.2

Search every single control of the Options page, no "script" button
Search all the add-on page, no script importing guide
Search all the forum and FAQ, no script importing guide
Search whole web using google, still no script importing guide
Click on x-notifier button, click Help, nothing happened

Shitest add-on I ever met that can't even explain itself

Firefox 클린 설치후 기존 사용 애드온과 설정을 동일하게 한후 4.0.3 사용시 정상 작동되나 Firefox 동기화(Sync) 하는 순간 4.0.3은 먹통이 됩니다. 참고하셔서 고쳐졌으면 좋겠네요.
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Answer to ononoma :
total re-install
Yes.
No.

Megint nem működik a gmail és a yahoo. 4.0.3 Az rss az igen.

saved account disappeared
and why POP3/SMTP is removed?

Why every time the application is updated, my accounts disappear?

The old version, 3.5.23, works perfect. Why does the newer versions doesn't show my accounts? Everyday I have to roll back to the previous version...

now since version 4.2.16 is working fine again with gmail, Outlook, Aol, & Yahoo ... pretty nice Add-ons ... keep it rolling & thanks for all developments

Everyone seems to to directing their frustration at the developer. He has worked without much reward for many years to give you this.

It is Google and Firefox that keep breaking this great add-on. Send your anger to these 2 and thank Mr Kang for still trying to get fixes done though it sometimes takes a few versions to get things right again. Then in a few months Google, Yahoo, etc will break it again.
Personally I would give Mr Kang a 5 stars at all times.

This new version is still rubbish, I thought you had resolved the problem but now you did it wrong again! How is possible that you are not able to fix this problem? I am completely amazed.
So the only option I have is to continue using the Version 3.5.23, which forces me to install it everyday.
Good job, man. Good job making rubbish.

I had personally to return back to FF42, taken ""volunteering"" all the security risks, because the FF's guys decided to "offer" me more security by messing up all my add collection, almost all my FF desktop and eventually all my every day working life. That is even far beyond an annoying and stupid paternalism - this is dictatorship!!!

As I am seeing it, unfortunately we all are doomed. Our big problem consisted in two points:
a) FF is still by far the best browser for anyone who wants to works seriously in internet, comparing with all the other browsers in the market.
b) FF lately totally sucks!!!

this add-on is now rubbish it does not work with firefox and develeoper can not be bothered updating it. it is a dead add-on

Great addon but how does one stop this spam page that keeps popping up with your addon?

When one contributes, one should do so without expectations

Please stop this from showing

http://xnotifier.tobwithu.com/updated.php?br=ff&ver=4.0.2

Doesn't work for Google on FF

Don't working for google mail.

Guys, please add as minimum some customization about the font color. It is the minimum because currently your new something work only with standard Firefox skin. Currently I am using dark skin and I can read noting in your menus.
As big second problem for me is support for two different accounts in same mail server. these are accounts in gmail.
As third Hotmail working on time to time.
Please do something or stop it forever because this transformation from one of the best Add-Ons to something strange is not good for anyone.

Not working!

The new version doen't work either. I have used the add-on for years and I really like it. it's a shame it broke.

Don't even bother downloading the latest version of X-notifier it's horrible. I just tested the 3.5.23 on the latest Firefox 53.0 (64.bit) and it's working great. Here are some tips you should do after you reinstalled 3.5.23.

Simply open Firefox click tools>addons>Extentions>
Click on the gear symbol> Then Uncheck "Update add-ons Automatically".

Otherwise If you don't Firefox will Automatically install the latest version again.

While your there you might as well go to Advanced>Update>"Check for Updates,But let you choose whether to install them". This will Prevent Firefox from automatically updated the latest version until your ready to install it.