Hi MRiney127, did you mean using the '''Thunderbird''' email software, or using a '''webmail''' site in Firefox, like Outlook, Gmail, or Yahoo? If it's for Thunderbird, a moderator can move your question over to that board. If it's for webmail, it would depend on the site: some might have this built-in, while others might allow you to inject HTML into a message while you're composing it (either by pasting it or using a "bookmarklet" which is a script you save as a bookmark for quick access or an add-on).