I've been using Thunderbird for years now and the problem that has always existed is the apparent unpredictability of the fonts setting and what happens when an email is created, sent to another email user, who may or may not be using Thunderbird and then the email is returned to the originator in a reply. It is clearly not WYSIWYG. The problem still remains that if you are using a high resolution screen you have to have font sizes set to quite small, when the receiver gets the email the font is large, if the email comes back to you it is in a larger font. This even occurs if you email yourself . I was creating a document the other day that required sections of other documents to be copied and pasted into the body of the email. I used “paste without formatting” and to be sure selected all the text and set all the fonts to be the same. The sent email content was returned in the reply and the various cut and pasted sections were different font types different sizes. Clearly “paste without formatting” hadn’t stripped out all the font artifacts and they were returned and Thunderbird used them. Under Tools/Options/Fonts and Colours/Advanced what is meant by size? 12 what is it points or pixels? If it is pixels surely it should be points? Then you are more likely to have a consistent experience for both the sender and receiver if Thunderbird was to use point sizes? Either way there is clearly something wrong that shouldn’t need the complex description here [[http://kb.mozillazine.org/Font_settings_in_Thunderbird|http://kb.mozillazine.org/Font_settings_in_Thunderbird]] Please make it truly WYSIWYG