I'm using a X13 ThinkPad with 1920x1080 resolution on a 13'3 display with Linux (Arch) and XFCE desktop. For the best results I've increased the XFCE's DPI to 134 and fonts sizes to 10. It looks like the fonts of the size ~13 without DPI change. It's fine, and applications like Firefox like those settings. In Thunderbird I've set the font size (interface) to 12 and in Settings the default font sizes for Latin and Other Writing Systems to 12 (both) and finally the interface font as well as plain text email and HTML e-mails without font sizes specified explicitly look natively and perfectly. But there are some senders using clients that generate HTML e-mails and specify the font explicitly as 'font-size=12pt' in their body by default. The same as my 12 so everything should be fine. Unfortunately font in those e-mails is really HUUUUGE! I'm wondering if there is some setting that allows custom scaling but only the HTML messages. Or some pt to px custom scaling for HTML? Or some maximal size allowed in HTML?