Image
In the context of email marketing, an image is any visual asset included in an email message, whether a photograph, illustration, banner, logo, product shot, or animated GIF.
Email images are typically hosted on a remote server and loaded when the recipient opens the email, rather than being attached to the message. This keeps file sizes manageable and allows marketers to track whether images were loaded, as is also the case with traditional open-tracking. Many email clients block images by default, meaning a significant portion of recipients will see your email without any visuals unless you design for that scenario.
Images in email serve multiple purposes: they reinforce brand identity, break up blocks of text, showcase products, and draw the eye toward calls to action. But they carry real technical constraints. A high image-to-text ratio can trigger spam filters. Large image files slow load times and increase data usage on mobile. An email that relies entirely on images to convey its message becomes completely unreadable when images are blocked.
The practical rule for B2B email marketers is to treat images as supporting elements, not the primary carrier of information. Your email’s core message should be legible in plain text. Every image should have descriptive ALT text that conveys its meaning even when it cannot be seen. And every image you include should earn its place by making the email clearer, more compelling, or more on-brand, not just more colourful.
Why do images not display in some emails?
Many email clients, including Outlook and some versions of Gmail, block images by default until the recipient actively chooses to display them. This is a security measure to prevent tracking pixels from loading automatically and to protect against malicious image links. It means your email must communicate its value through text and ALT tags alone until images are enabled.
What is the recommended image size for email?
A common guideline is to keep the total file size of all images in an email below 200KB to avoid slow loading and potential spam filter triggers. For individual images, aim for widths of 600 to 650 pixels (the standard email content width) and compress files before embedding. Use JPEG for photographs and PNG for graphics with transparency.
What is ALT text in an email image?
ALT text is the descriptive text that appears in place of an image when the image cannot be loaded or is blocked by the email client. It is written into the HTML of the email as the alt attribute on the img tag. Good ALT text describes what the image shows and, for call-to-action images, restates the action the image is prompting, so the email remains functional even without visuals.