I have my thunderbird set up to use HTML as I use frequently, but I also like to use Plain Text on specific occassions:
I also make sure all my emails are sent in both formats, sothat the recipient can also choose how they wish to read the message. Tools > Options > Composition > General tab / Menu icon > Options > Options > Composition > General tab
If you have specific people in your address books who always want to receive in Plain Text format, there is an option to set this up.
If I click on 'Write' it will always offer the HTML format. However, if you hold down Shift key + click on Write, it will open in Plain Text format.
wrap and make configure the following settings to be:
0 (zero)Possibly also:
- mail.wrap_long_lines:
false- plain_text.wrap_long_lines:
false