Image blocking is increasing in popularity with service providers as well as individuals. Blocking occurs when either the service provider or the email client an individual uses stops images from displaying when the email is being read.
As you can imagine image blocking can have a critical effect on an email campaign if the creative being used depends chiefly on images to convey its message.
Usually the image is replaced with a border and a small red x in the upper left corner. The newest versions of Outlook (Outlook 2003 and Outlook Web Access), and other email clients (AOL versions 6 through 9, and Thunderbird), are installed with image blocking enabled by default. Therefore, your email recipients who use these email clients must turn the image blocking off in order to view images you send in an email. Believing that users are capable of knowing they need to turn blocking off and being able to accomplish this task is usually a long stretch. Additionally, many Email Service Providers, such as Yahoo, are giving their online users the ability to block images when using their web email viewers. Again, some providers, such as Gmail (Google’s e-mail service), has imaging blocking turned on by default. Similarly, you are relying on the recipient to be able to turn image blocking off. AOL goes one step further, AOL blocks the entire email and returns a non-delivery message to the sender. With AOL’s method the user must activate the filter, but after it is activated the intended recipient does not even know he is missing email.
Another issue with image blocking will cause the open rates, based on image access, to under count true opens that may be occurring. Typically, email opens are tracked by counting the accesses on an image, or through the use of a web beacon program. These images and beacons are placed in the HTML code within the email creative, inside <img> tags. These are the same <img> tags that are blocked when recipients have image blocking enabled. Therefore, image blocking defeats email open tracking.
Even when images are blocked, there are methods, which can be used to track opens, although the solutions do not work across the board with all ESP’s and email clients. HTML allows the web beacon program to be placed in other HTML tags such as the <link rel="stylesheet"> have an src attribute that can be used to call the web beacon program. Using the <link rel> tag in this manner works with Outlook 2003, and Hotmail, but does not work with Gmail, or Yahoo. Because of the variation between ISP’s, ESP’s, and email clients, diligence must be taken to
continually monitor the e-mail marketing environment for tags that work and those that do not. Because images used to convey meaning might be
blocked, attention should be given to other means within the ad copy to accomplish marketing goals. Creative copy in an e-mail can be formatted with HTML code to convey messages through the use of font size, color and style. This type of HTML will display properly in all e-mail viewers even when image blocking is enabled. By using bold fonts, color and great copy, an email creative can still move a recipient to action. When developing an email marketing creative, attention should be paid to how the e-mail displays with and without images.
Many email marketers try to circumvent the image blocking problem by asking the email recipient to add the email URL to their email client address book, and thereby join the user’s email client whitelist. This can be effective, but only under two circumstances, you can convince the recipient to take this action, and if the e-mail reaches the intended recipient in the first place.