Font settings in Thunderbird are a little tricky

 Font settings in Thunderbird are a little tricky. These settings work for me.

 

1) main menu bar

  View > Character Encoding > Auto-Detect > set to "Universal"

2) View > Message Body as > set to "plain text"

3) Tools > Options > Display > Formatting > set preferred default fonts and sizes

4) Tools > Options > Display > Formatting > Advanced

a) Western Page

set fonts and sizes as desired

tick "Allow messages to use other fonts"

tick "Use fixed width font for plain text messages"

Outgoing Mail UTF-8

	   Incoming Mail UTF-8

untick "When possible use the default character encoding in replies"

b) On "Fonts For" drop-down menu repeat the procedure for Unicode and Central European.

c) On "Fonts For" drop-down menu select "User Defined" and repeat the procedure.

This will cover most messages, but you may have to repeat this for any other character encodings that cause you problems. For example, messages in ISO 8859-7 will mean you have to change the "Greek" page too. If you don't know which character sets correspond to the Thunderbird pages they're all on Wikipedia and elsewhere.

5) Go to Tools > Options > Advanced > Config Editor

mailnews.force_charset_override false

6) Folder Properties

Default Character Encoding User Defined

Uncheck 'Apply default to all messages'.