I have been searching far and wide for an answer and am stuck here: https://support.mozilla.org/en-US/questions/1368273 This solution doesn't work for Thunderbird 102.11.0 because there is no OTHER WRITING SYSTEMS. I have set LATIN on font and size, composition is set to HTML. Variable width is set, but if I change this to a specific font, it still shows something different than the font I've used to compose, so it doesn't seem to help. Sent files show Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: 8bit Why is it so hard? I want my sent files to look like my composed files as much as possible. For example, if I use a serif font to compose, I want a similar or, if available, identical serif font, for readers if they use HTML as well. Thx in advance.