It's not easy to cut through the spam and deliver an engaging email, even if the recipient has opted in. I've done many emails over time, and they've have had to adhere to the rules of designing emails. The use of images, the dimensions of the email itself, the way it's coded, which email clients are being used, if the information is above the fold - these are all important factors that have to be considered when creating an effective email. Here are examples of some I've put together.