But are you sure your readers are seeing what you see?

In a recent survey by Epsilon, 48 percent of respondents said that the images in their email clients are "sometimes or always" turned off. Experts expect this number to increase in 2008, as fears of viruses and spyware increase. And, with email clients and platforms getting more sophisticated many of your readers will have image suppression set as their default.

The only way to guarantee the success of your next email campaign is to assume that none of your readers can see any of your images. Sure, it sounds harsh - but do you really want to risk alienating over 48 percent of your subscribers?

By following these best practices, you can ensure better results with your next email campaign:

1. It is critical that you use images to support your message, not convey your message. Never use an image as a headline, or in place of text. Never use an image to express an idea that is not repeated in the copy.

2. Always include an alt tag with all of your graphics. And be sure the tag is descriptive enough to actually take the place of the image. Also, adding captions to any applicable images will help in two ways: first, it will provide necessary information to readers who can not see your image, and secondly, eye tracking studies prove that captions do get read a majority of the time.

3. Be sure to tell your subscribers how to turn the images on in their email clients. I suggest creating a confirmation page with whitelisting instructions and image display instructions. Take your customer to this page immediately after he subscribes to your mailing list. Repeat the instructions in your confirmation email.

4. Create a web-based version of your email and include a link to it in each of your campaigns. Many readers want to see your graphics, but they don't want to take the time - or they don't know how - to adjust their email clients.

5. Always offer a text only version of your email campaign during the subscription process. And, since some readers will be accessing their email from multiple clients, such as Outlook when they're in the office and web mail when they're on the road, include a link to the text only version in each of your html campaigns.

As hackers and spyware and viruses become more prevalent and email clients become more complex, it is important for marketers to stay on top of the best practices and conventions. So, follow these steps for now in all of your email marketing campaigns, but beware, the rules are sure to change sometime in the near future.