“Failing to add an image description can hurt you in the long run in terms of email performance. Because many email providers block images, the viewer will instead see the alternate text or text description in place of the image. This is also true if the images fail to load or if the connection is poor when the individual opens the email. The alternative text that appears essentially guides the reader through the email in case the images fail to appear.”
Never place images in emails without adding descriptions. Images are frequently blocked by email providers, or fail to load correctly. Rather than having huge blank spaces in your emails, include descriptions. They act as image “replacements” when necessary and provide more information for the subscriber.