Email support for HTML is rather limited. For example, HTML email does not support:
- JavaScript
- Video
- Plugins
- Java
- Many CSS3 selectors and properties
We recommend against using apps that are designed to author web pages to create your email messages, since the HTML code that these apps create will, most likely, not work in email.
If you want to hand-craft your own HTML email, Campaign Monitor has a great chart of email client support for CSS properties and selectors. Direct Mail will automatically inline CSS styles when your message is sent (or previewed), so you can keep your HTML clean and your CSS content separate while crafting your email. You can use the Preview window and our design test feature to see what your email will look like in a variety of email clients.