People simply will not read lengthy e-mails. If you don't get straight to the point in the first few sentences, you risk having readers delete your mail before they find out about your products and special offers. Learn to express yourself concisely so you don't waste people's time.
It may even be worth your while to acknowledge that people are bust and that your message will not take long to view. In fact, if your product or service is geared to a particular niche, you might even say that upfront. For instance: "If you are hearing impaired, then this service will make a big difference in your quality of life." In other words, let the reader know who the message is really for.
Excerpted from 303 Marketing Tips: Guaranteed To Boost Your Business