Firefox doesn't do email, it's strictly a web browser.

If you are using Firefox to access your mail, you are using "web-mail". You need to seek support from your service provider or a forum for that service.

If your problem is with Mozilla Thunderbird, let us know and we can move this thread to the Thunderbird queue. This question currently is in the Firefox queue for answers.

Make sure that you haven't enabled a High Contrast theme in the Windows/Mac Accessibility settings.

Make sure that you allow pages to choose their own colors.

• Tools > Options > Content : Fonts & Colors > Colors : "Override the colors specified by the page with my selections above:"

Try "Always" if the default "Only with High Contrast themes" isn't working.

Note that this affects background images.

See also:

• https://support.mozilla.org/kb/Websites+look+wrong
• https://support.mozilla.org/kb/Website+colors+are+wrong