Email, Messaging, & Video Calls Email How to Edit the HTML Source of a Yahoo Mail Email HTML editing is not supported in the current Yahoo Mail version by Heinz Tschabitscher Writer A former freelance contributor who has reviewed hundreds of email programs and services since 1997. our editorial process Heinz Tschabitscher Updated on January 30, 2020 Justin Sullivan / Getty Images Email Yahoo! Mail Gmail Tweet Share Email It's no longer possible to edit HTML in Yahoo Mail messages. However, Yahoo Mail has a rich text editor that alters the appearance of text, inserts links, and adds emoticons. If you use Yahoo Mail with Internet Explorer on Windows, make easy use of rich formattings like boldface, custom fonts, or graphical smileys. Even if you do, not all of the HTML richness is available, and even if you don't, you can use HTML formatting in Yahoo Mail. Yahoo Mail lets you enter HTML code in email messages. If you know at least some basic HTML coding, this is a flexible way to customize and enrich your emails. Edit the HTML Source of a Yahoo Mail Email You are Composing To edit the HTML source of a Yahoo Mail email you are composing, select View HTML Source. If View HTML Source is not available — it is only available when the rich text editor is active — select Allow HTML tags instead.