- Responsive Email Resources: www.ResponsiveEmailResources.com
- Bulletproof Buttons: www.buttons.cm
- Bulletproof Backgrounds: www.backgrounds.cm
- HTML Email Boilerplate: www.http://htmlemailboilerplate.com
- Special characters for HTML Email: http://www.emailonacid.com/character_converter/
- Send HTML Email with Google Docs: http://www.labnol.org/internet/send-html-email/19672/