Have you filed bugs about this, with the example emails attached? Thunderbird uses the same exact HTML/CSS renderer as Firefox. To the extent that it's not re

Have you filed bugs about this, with the example emails attached? Thunderbird uses the same exact HTML/CSS renderer as Firefox. To the extent that it's not rendering mails "properly", those mails are clearly expecting to be rendered in a way different from what the HTML/CSS standards say... It's possible to make this work, if needed, but the developers would need to at least know what standard-deviating behaviors are needed.