The rules of email building
One of the major challenges to be overcome when building emails is ensuring that they render correctly. This can be difficult because there are so many ways to view emails ranging for dedicated email software such as Outlook (which is currently on it 12th version) to webmail solutions (Hotmail, Gmail, Yahoo! Email) running in any number of browsers. Here are a few key rules I try to follow.
1. Keep it simple
The more complicated your email the more things that could potentially go wrong. Simpler emails have a greater probability of rendering correctly and layout features that would be consider simple in websites like having text wrap around an image or use of background images can cause problems. Try to use a simple grid format and avoid too much css.
2. Use inline styles
Although webmail solutions are capable of using style sheets programs such as Outlook have a nasty habit of ignoring them. Perhaps the best way to style you emails in through inline styles which are consistently supported.
3. Consider your audience and test your email thoroughly
It's always worth considering your audience when designing and building your emails, try to imagine how they will access and use the email (will they print it, forward it to a friend, etc) and test to check it works in those situations.