Remove vertical spacing between images in Mozilla Thunderbird
If you have set an align attribute in an image to right or left, Thunderbird will add a 3 pixel margin these images.
Thunderbird HTML codes
Target Mozilla Thunderbird using .moz-text-html CSS Class
You can target the Mozilla Thunderbird email client by including the CSS class .moz-text-html, which Thunderbird wraps around the contained email.
Prevent borders on linked images
Some email clients and webmail services such as AOL Mail, Gmail, Lotus, Outlook, Thunderbird, and Windows Mail will display a blue or black border around images that are linked but don’t have a border specified.
