"It's quite a conundrum for marketers," Nussey said. "Just as broadband penetration begins to reach deep into American households, facilitating the display of rich imagery in emails, a growing concern about security and spam has caused new focus on blocking HTML images."

He said today's emails must pass through a virtual gauntlet of filters and firewalls before reaching recipients' inboxes. And with a number of email clients, those filters block the rich images that help sell products and services.

Silverpop's "2005 Broken Link Study" reviewed messages sent by 360 of the largest US companies in nine major industry segments. Companies selected for the study were those identified by Dun and Bradstreet as the top revenue producers in their segments.

A team of researchers, under the guidance of Silverpop's Strategy Group, registered to receive emails for eight popular email clients. These included:

-- AOL 8.0+

-- AOL 9.0

-- Earthlink

-- Gmail

-- Hotmail

-- Outlook 2003

-- Outlook Express 6

-- Yahoo!

Each message was viewed using the default settings of the various email clients and then compared and evaluated in terms of how the message displayed.

Following are a few of the key findings:

-- More companies use email to communicate to prospects and customers than three years ago. In 2005, 71 percent of companies studied offered publicly available email marketing subscriptions, up from only 30 percent that offered emails in 2002.

-- More companies are sending HTML emails; 47 percent sent them in the 2002 study compared with 69 percent in 2005.

-- However, the percentage of broken emails hasn't changed significantly; 40 percent of the emails reviewed contained missing graphics, compared to 42 percent in the 2002 study.

"While HTML-based email provides a richer product experience for consumers, the benefits that accrue from HTML are obviously lost if the images and links are not functional," Nussey said. "In fact, mis-rendered HTML messages can not only perform worse than their text-based counterparts, but can have a net negative impact on both brand perception and the health and size of your list."

He pointed out that there are a number of processes that, if routinely implemented, can improve not only renderability but response rates as well. For example, he urged email marketers to ask to be added to recipients' address book.

"Not only will your email messages arrive in inboxes with images intact, they'll move through ISP filters with much greater reliability," he said.

Others recommendations included to include a link to view images via a Web version of the message, and to know before you send what your email looks like without any images.

"Ultimately, the problem with broken images is a problem of broken promises," Nussey said. "Consumers sign up to receive your emails because you initially offered to deliver something interesting and relevant. If you keep that promise, recipients will add you to their address book, smoothing the way for your messages. If you fail to deliver as promised, be prepared to suffer the consequences."

To receive a copy of Silverpop's "2005 Broken Link Study," visit www.silverpop.com.

About Silverpop

Silverpop is a leading provider of permission-based email marketing solutions, strategy and services, with offices throughout the United States and in the United Kingdom. For the second year in a row, in 2005 JupiterResearch ranked Silverpop as the email service provider with the highest overall value for emailers with lists of over 150,000 recipients. Jupiter's annual evaluation of email service providers said "Silverpop offers one of the most complete email marketing applications, and together with its very usable interface, makes an excellent value for marketers."

Silverpop helps marketers cultivate and maintain long-term strategic relationships with customers and partners by maximizing the potential of email as a relationship tool. Its flexible service model allows marketers to choose from full service or ASP and easily move between the two, making it an ideal solution for any stage of an email program. Silverpop provides email marketing to industry leading companies including Fossil, The Bombay Company, British Sky Broadcasting, Weather.com, Golfsmith and more. Best practices and white papers are available at www.silverpop.com