each email contains information as to the character set it is using. generally this is utf-8 or utf-16 because they are standards that will see a mail displayed in almost any language or chracter set.

If every time you read a mail you need to fiddle with it, there is a problem, but it is not with Thunderbird. It is with the sending mail system as it is apparently not capable of correctly encoding an email. In the body of the mail at the beginning of the encoding section you will find a header that looks like

Content-Type: text/plain; charset="utf-8"
MIME-Version: 1.0
Content-Transfer-Encoding: 7bit

or this is for an HTML part.

Content-Type: text/html; charset="utf-8"
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit

Do your mails, which appear to be in utf format actually specify something else?

Or and this is a big one, you do not have appropriate fonts installed and the system is failing back to another member of the font family that is not unicode.

This account is a POP3 mailbox with "Big5" character encoding. ( one of 8-bit character set )

The same problom occurred in the older version too.

But we can set the folder's " Properties " to fix wrong encoding before.

There's no same option in Tb91. ( or maybe I forget where it was )

• The attached image is Thunderbird v78.14.0.

have a look at this bug. https://bugzilla.mozilla.org/show_bug.cgi?id=1690395

perhaps it would help if I linked to the correct bug. https://bugzilla.mozilla.org/show_bug.cgi?id=1713786

You might be able to determine if that fix applies to your problem.

perhaps it would help if I linked to the correct bug. https://bugzilla.mozilla.org/show_bug.cgi?id=1713786 You might be able to determine if that fix applies to your problem.

Thank you, Matt.

It seems that Folder Properties " Fallback Text Encoding " is lost from Tb91.

And I am not sure how to use the pacth " 1713786-fix-repair-charset.patch ".

https://github.com/Betterbird/thunderbird-patches/blob/main/91/bugs/1713786-fix-repair-charset.patch

Another problem is, if I upgraded to Tb91, I can't downgrade to old version with the same profile. Tb91 changed something to avoid using old version, so profile changed too.

By the way, I couldn't find the same General option " Text Encoding " sfhowes said in the attached image in this thread.

" Preventing mojibake with HTML emails "

https://support.mozilla.org/en-US/questions/1247134

It seems Tb91 removed this option too.

Install it ，"Charset Menu”，in Thunderbird 91.0.3, then you'll got the menu [Text encoding]- then choose [big5,gbk,utf-8,....] The menu is back now.

Install it ，"Charset Menu”，in Thunderbird 91.0.3, then you'll got the menu [Text encoding]- then choose [big5,gbk,utf-8,....] The menu is back now.

It's not good to remove the feature completely.

1. Add-ons "Charset Menu" It needs changing charset EVERYTIME.

2. Folder Properties " Fallback Text Encoding " It's OK for the users who are using CJK charset, doesn't it bother anyone? I don't know, also I don't know why TB team removed it COMPLETELY.

3. Tb91 couldn't downgrade to old version I tried downgrading to Tb78.14, but Tb91 changed something (maybe pref.js) and I didn't backup before, so I CAN'T DOWNGRADE OLD VERSION.

How to downgrade (Japanese)

https://forums.mozillazine.jp/viewtopic.php?f=3&t=18665#p68967

Delete the file in the profile folder " compatibility.ini "

sdoger said

Install it ，"Charset Menu”，in Thunderbird 91.0.3, then you'll got the menu [Text encoding]- then choose [big5,gbk,utf-8,....] The menu is back now.

It's not good to remove the feature completely.

1. Add-ons "Charset Menu" It needs changing charset EVERYTIME.

2. Folder Properties " Fallback Text Encoding " It's OK for the users who are using CJK charset, doesn't it bother anyone? I don't know, also I don't know why TB team removed it COMPLETELY.

3. Tb91 couldn't downgrade to old version I tried downgrading to Tb78.14, but Tb91 changed something (maybe pref.js) and I didn't backup before, so I CAN'T DOWNGRADE OLD VERSION.

Maybe you should uninstall TB91 first, then install Tb78. It's inconvenient for users to choose encoding sometimes. Somebody said:"The soft name “foxmail” doesn't have this problem." Maybe we shoud replace Tb with FOXMAIL, I don't know. :)