Rated 5 out of 5 stars

WORKS, and and that includes the British version as well.

SOLUTION:
You can't use the [download-button] to add the dictionary file to your programme. Or in my case, a new clean thunderbird (ver 31) install.

Give the developers a break, it does all work, but sometimes you have to work at it to get it right. If the button doesn't work, then right click it and download the file->link to a directory.

Go to the add-ons manager, and select install from file (do it from where you saved that *.xpi file)

Accept all warnings. Restart the programme, and - volar' - you now have your spell-checker installed.

Very useful, and free, and just brilliant.

This review is for a previous version of the add-on (7.0.1). 

Rated 1 out of 5 stars

I was unable even to download it . I press download button but nothing happens . Thunderbird localization is Russian .

This review is for a previous version of the add-on (7.0.1). 

Rated 5 out of 5 stars

Что тут за дебилы в комментах по отписались? Один в почтовом клиенте не нашел, другой тупой что не может понять как работает дополнение и ставит 0 - это просто уму не постижимо. Спасибо за дополнение, очень полезно иметь подсказки правописания на английском. Все работает как надо и где надо.

This review is for a previous version of the add-on (7.0.1). 

Rated 1 out of 5 stars

0 stars, I don't see the spell check Icon any where on the FireFox tool bar.

This review is for a previous version of the add-on (7.0.1). 

Rated 1 out of 5 stars

I'm wondering why the authors aren't verified on Thunderbird.
I was about to install this add-on and got the msg that they're NOT verified and so you install at your own risk.
How much effort does it take to verify yourself with Thunderbird?
It would seem the logical thing to do.

This review is for a previous version of the add-on (7.0.1). 

Rated 5 out of 5 stars

To the developer: There was a confusion. I tried to install this dictionary on FF for Android and got an error message. It's dawning on me that may be it's not intended for Android, is it?

This review is for a previous version of the add-on (7.0.1). 

Rated 5 out of 5 stars

Seems Mozilla has messed something up.

This review is for a previous version of the add-on (7.0.1). 

Rated 5 out of 5 stars

Good, i am Brazilian user and i approve this. 5 STAR(like a GTA 5)

This review is for a previous version of the add-on (7.0.1). 

Rated 4 out of 5 stars

Please add this words:
Galicia
Galician

This review is for a previous version of the add-on (7.0.1).  This user has a previous review of this add-on.

Rated 5 out of 5 stars

A good instrument for dealing with short texts, as it checks the text and show suspected spelling mistakes.

This review is for a previous version of the add-on (7.0.1). 

Rated 1 out of 5 stars

does not work with FF v.25

This review is for a previous version of the add-on (7.0.1). 

I'm using United States English Spellchecker together with Firefox 25 beta 7 and it works properly.
Try it by creating a new clean Firefox profile.

Rated 5 out of 5 stars

Works perfectly with Fx 24. Thank you.

Is it possible to activate checking in ALL text fields?

Could you please add an option to convert "i" to "I", and first letters in sentences to Capital letters?

This review is for a previous version of the add-on (7.0.1). 

Rated 2 out of 5 stars

Contrary to what the developer claims, this add-on works only intermittently with Thunderbird since upgrading to V24. If the bug is the problem why wasn't a problem before V24?

This review is for a previous version of the add-on (7.0.1). 

The problem with Thunderbird depends from a specific Thunderbird bug: https://bugzilla.mozilla.org/show_bug.cgi?id=812638
I can't do anything else than waiting for the bug be fixed.

Rated 1 out of 5 stars

United States English Spellchecker 7.0.1 .. keeps disengaging.. It hasn't worked for me..once I reinstall it works, when close everything out and come back to Firefox later, it doesn't work and I have to reinstall again..

This review is for a previous version of the add-on (7.0.1). 

I'm using it right now and it works properly. Try it in a new profile. You'll see it will work fine.

Rated 1 out of 5 stars

Loved it until I upgraded to FF 24. It doesn't work. It just keeps asking me to install it over and over again even though it reports it installed successfully.

This review is for a previous version of the add-on (7.0.1). 

I'm using it right now and it works properly. Try choosing the language you want by right clicking in a text field and select English (United States).

Rated 5 out of 5 stars

This spell-checker makes typing easier.
Works well with FF23.0/Windows XP SP3

This review is for a previous version of the add-on (7.0.1). 

Rated 4 out of 5 stars

Works with version 21 PC XP and Win7

This review is for a previous version of the add-on (7.0.1). 

Rated 2 out of 5 stars

Add-on not compatible for FF v21.0 on Sprint Galaxy S3.

This review is for a previous version of the add-on (7.0.1). 

Rated 5 out of 5 stars

I find this spellchecker very useful since I am a not-english spoking person. Thank you!

This review is for a previous version of the add-on (7.0.1). 

Rated 2 out of 5 stars

will not install after download. pops up a message that it's not compatible with Firefox for android version 20.0.1
EDIT: Just tried again after developer response and same problem. tells me it can not install because it's not compatible with 20.0.1. I'm running Android Jellybean 4.1.1 on a Acer A210 tablet.

This review is for a previous version of the add-on (7.0.1). 

The add-on will install properly.
I've just tried with Fx 20.0.1 and it works like a charm.