character encoding problem

[Mpls_novice]

Hi,

I need help solving a character encoding problem. I am using Thunderbird (52.6.0) on a Windows 10 Enterprise machine to send Yahoo! mail. Until recently, I have had few problems over the years.

Currently, however, when I send a test email to myself from yahoo online, the special characters in my email (such as accents and umlauts) are encoded correctly online and in Thunderbird. But when I send the same test email to myself using Thunderbird, the special characters in my email are incorrectly encoded - they get replaced by "??" - both when I open the email online and when I open the email in Thunderbird. When I open the mail saved in my "sent" box, the special characters are correctly encoded. Furthermore, when I receive an email from a third party, the special characters are correctly encoded when I open the mail in Thunderbird. But when I reply to the third party, the special characters in the copy of their email in my reply (and, of course, in the text of my reply) are incorrectly encoded once the mail is sent - they get replaced by "??".

My Thunderbird encoding settings are set to:
mainews.send_default_charset - default - string - UTF-8
mailnews.force_charset_override - default - boolean - false
intl-fallbackCharsetList.ISO-8859-1 - default - string - windows-1252
intl.charset.fallback.tlk - default - boolean true
intl.charset.fallback.override - default - string
mailnews.view_default_charset - user set - string - UTF-8
mailnews.reply_in_default_charset - user set - boolean - true
mail.default_charsets.migrated - user set - integer - 1
intl.charsetmenu.mailview.cache - user set - string - ISO-8859-15, windows-1252, ISO-8859-1, UTF-8, ISO-8859-2
intl.charset.detector - user set - string

None of these attempts solved the problem:
Changing the language of the text
Ticking or unticking "When possible, use the default text encoding in replies"
Restarting Thunderbird
Reinstalling Thunderbird
Deleting and settting up the mail account again from scratch

I would be most gratefulf for some help. I am not very computer savvy, but I can try to answer questions and try things out.

Thank you!

[tanstaafl]

Are you using a free yahoo account or one provided by AT&T? There is a related thread at http://forums.mozillazine.org/viewtopic ... &t=3038519 which appears to be due to a problem with the AT&T server. Too soon to tell yet.

Do you have any other accounts? For example, Gmail, Outlook, Zoho or GMX. If so it would be useful to know whether they have the same problem.

[Mpls_novice]

Hi tanstaafl,

I am using a free yahoo! account and have no association with AT&T.

As to your question about other accounts... when I send an email with special characters from a corporate email account to my yahoo! account (both set up in Thunderbird), the special characters are displayed correctly. However, when I forward that correctly encoded mail from yahoo back to yahoo using Thunderbird, the special characters in the originally correctly displayed email get replaced by ??.

Is it correct to think that the problem is not being caused by a yahoo server somewhere because when I send mail from the same yahoo email address online, the characters are displayed correctly.

And is it therefore correct to deduce that the problem must be related to the way my yahoo account is set up on Thunderbird?

[Mpls_novice]

I have found a solution or a workaround on mozillazine that appears to solve my problem:

http://forums.mozillazine.org/viewtopic ... #p14792921

In Configuration Editor, scroll down to mail.strictly_mime Click on it to change if from False to TRUE.