Check your email for spelling and grammar mistakes.
Are all the adjectives, adverbs and other words used really necessary?
Does the email have a logical structure to support your main message?
Does your email address the needs and interests of the reader?
Does your email attract the interest of the reader in the beginning by stating something that is of interest?
Does your email end with an appeal or call for action?
Have you included a closing remark to strengthen your relationship?