Installing a new version of Thunderbird does not change content in the profile. Even so, I always copy appdata\roaming\thunderbird to another location prior to doing that.

Thank you David, In this case, how do I process to change the version in another language? Have I to uninstall the US version before installing a brand new version, keeping all my profile? As you recommended, I have copied my profile in another folder.

You help me improve.

You could probably just install the french over the english, as they would have same filenames. But, it's cleaner to uninstall first. Your first priortity needs to be that the new version is not older than the current version. That is, if the english version is 147, don't install the 140 version to replace it.

This is OK, The English is 140, and I want to install a French 147 over it. Thanks.

I saw that my question was duplicated. I am sorry, but it was due to an error message received from the Mozilla server telling me to retry after 30 seconds. I didn't know the first message was already sent.

147 is fine; you will be getting updates more frequently, and if you are heavily dependent on addons, there may be occasional delays. 140 focuses on stability, and will not receive new features except annually. If you have problems with the upgrade, let me know.

Just install 147 french over top of 140 english. There is no risk, however a) as david mentions backup first for safety, b) if you have add-ons at all, install https://addons.thunderbird.net/en-US/thunderbird/addon/addon-compatibility-check/. If you have any that are even partly based on experiments, then you probably shouldn't run the release version but rather stay with ESR.

Please know that we have support articles that cover backups and many other topics. https://support.mozilla.org/en-US/kb/profiles-where-thunderbird-stores-user-data#w_backing-up-a-profile

Thank you Wayne,

Now I am not sure of what to do because the new version want to be installed in this folder: C:\Users\*******\AppData\Local\Mozilla Thunderbird instead of: C:\Users\*******\AppData\Roaming\Mozilla Thunderbird What to do? Change the folder or not?

Thunderbird installs content to BOTH locations, but the profile is in the roaming\thunderbird folder

To be clear, the locations you mention are for data, not where the program should install.

After installation of the French version over US in \Local, Thunderbird opened but failed, and my computer was stuck. I must restart. In fact, I have 2 folders in \Appdata\Roaming: \Thunderbird and \Mozilla\Thunderbird.

And the installer want to install in: C:\Users\*******\AppData\Local\Mozilla Thunderbird which is a new one!

Sorry but I am very confused.

I managed to install Thunderbird by uninstalling the 64-bit version. After that, the installer offered to install the application in \Program Files (x86)\… because I had a 32-bit version. So, I changed the destination folder to \Program Files\Mozilla Thunderbird\ and recovered my local folders at startup. I'm going to see how to organize my folders and transpose my management rules into this new product, and then configure my accounts to recover my emails.

I have a follow-up question: I use several languages and alphabets other than Latin in mails. Is this manageable in T-bird? Also in the contacts?

Thanks for your kind help. Michael (from France).

First, relocating the installation to \Program files does not change your 32-bit install to 64-bit. If you want the 64-bit, I suggest installing it. For the languages, if you mean to you correspond with people in multiple languages, there are multiple spell-checkers available. Or did I misunderstand? If you need assistance in recovering emails, we may be able to assist. I did not understand your last question about contacts. Thank you. I'm glad to have been able to assist.

Thank you David, I have installed the 64-bits version in the good folder. My 32-bits version was only used to import my Outlook folders, because it was not possible to import in the 64-bits version. Now I have recovered my folders in the good place.

All is correct, I don't use the 32-bits anymore. About the languages, yes, I correspond with foreign people, even in non-Latin alphabets (Cyrillic, Japanese for example). So I need to use Unicode everywhere, and also in my address book for the contacts' names.

I hope I am more understandable. Pardon my English ;)

This feature used to be more visible, I think, years ago, but I'm not sure of that. Anyway, in the config editor, check to see if this setting

 mail.strictly_mime    is set to true. If not click to change to true and then exit. to be sure you changed it successfully, reenter the config editor to verify.  the config editor is at settings>general and is at the very bottom right of screen. That should change all text to unicode. 

I also suggest setting all fonts for consistency. I did this some time ago, but still accurate. go through all steps to ensure that 'latin' and 'other writing systems' are exactly the same.

  https://support.mozilla.org/en-US/questions/1462509

And, you might be interested in a neat addon, unicodify. I use it to simplify writing to non-English names where umlauts and the like exist. Takes a little customizing and practice. It works by entering a \ where you want a special character and then toggling to the desired one. It's a little messy at first, but I can't imaging coping without it.

And your English is perfect. My French is horrid, all because I failed the subject in 10th grade because I was the only boy in the class and a sophomore, and all the other students were beautiful girls a year older. Grasping French didn't have a chance, as my testosterone was on overdrive at that young age. :) There, more than you wanted to know...

D

That was a great handicap!

And memories still make me smile. :) Enjoy your day. It was my pleasure to assist.

One option that you can do with both Firefox and Thunderbird is to install language packs. This way you can have one install but be able to change the language of the interface between two or more languages. Note the language packs do not have an affect on the spell checker as that uses dictionaries.

https://services.addons.thunderbird.net/thunderbird/language-tools/ https://addons.mozilla.org/firefox/language-tools/

Thanks, James, I never knew that. Good to know this flexibility. :)

Thank you James, I discovered these add-ons after the last discussion with David, looking at the parameters and I added several packages. Very easy, simple, and fast to load.

I will continue tomorrow to search other features and customize my T-bird. It's late now here, and I'm going to sleep. Have a nice evening!