Do not type in all caps. That’s yelling or reflects shouting emphasis.
If you bold your type, know you are bolding your statement and it will be taken that way by the other side – X10!
Do not use patterned backgrounds. Makes your email harder to read.
Stay away from fancy-schmancy fonts — only the standard fonts are on all computers.
Use emoticons sparingly to ensure your tone and intent are clear.
Typing your emails in all small case gives the perception of lack of education or laziness.
Refrain from using multiple font colors in one email. It makes your email harder to view and can add to your intent being misinterpreted.
Use formatting sparingly. Instead try to rely on choosing the most accurate words possible to reflect your tone and avoid misunderstandings in the process.