How to build an HTML email

This is just a quick summary on how to create an HTML email:

DON'T use:
- "div"
- "padding"
- "background-image"

DO use:
- images
- "background-color" -s
- "width" with exact px values
- "table" -s (even if normally you would use a "div")
- inline styles everywhere

This list will be expanded over time and experience or if you have some own rule-of-thumb please share it with us.