An estimated 95 percent of all commercial email messages are sent in HTML or in a multipart (combined HTML and text) format. Most e-mail includes at least a single external image, even if it's the open-tracking image, a clear, one-pixel GIF image used to track whether an e-mail has been opened.
Virtually all e-mail marketers host images on a Web server, rather than embed them within the message itself. To load images, a call is made back to the hosting server.
Disabled images also have implications for marketers, including:
* Lower open rates. Some recipients scan e-mail in the preview pane or open messages with images disabled.
* Image/content filter quandary. To cope with content and spam filters, e-commerce-oriented marketers sometimes place much of their copy within images to avoid being filtered. This could increase delivery rates but result in fewer recipients actually seeing the copy.
* Uncertainty caused by user-driven controls. Some ISPs and e-mail clients enable users to determine if they want images blocked.
Marketers can take a few steps to help minimize the issue:
* Add a "view Web version" link. Host a version of your message on the Web. Provide a text link to it at the very top of your message.
* Check message appearance in the preview pane. Can recipients can make a quick "open" decision based on content showing in the preview pane?
* Include alt tags. If images haven't loaded, properly written alt tags at least provide the recipient with a sense of what they doesn't see.
* Create text versions. With HTML e-mail so popular, text versions tend to be neglected. Yet recent e-mail client changes mean users have an increased ability to select which default format they prefer. A strong text version ensures you still reach users, regardless of format preference.
Blocked images should only be a minor nuisance for most permission e-mail marketers who provide real value to recipients. Deliver the best, most relevant, personalized content to subscribers, and most will want to view your entire e-mail with images, not just the text.