Help Centre

Images play a vital role in emails – whether it’s a logo, header image, icon, or product. They catch a customer’s eye and draw their attention. However, while it’s tempting to fill campaigns with numerous images, following best practices ensures your emails remain engaging, load quickly, and avoid spam filters.

What to avoid: Image-only emails

It can be tempting to create image-only emails, but these are a big no-no. This is for a few reasons:

Not mobile friendly - full images won’t dynamically resize on mobile - meaning your content will look either very small or very big on desktop.

Not accessible - images are impossible for screen readers to read, making them unusable for users who are partially sighted to read your emails.

Spam scores and filters - emails that are image and link-based only will immediately be much more likely to be flagged as spam. This is because email providers cannot read the content of your email and, therefore, cannot make a decision about its legitimacy.

Non-dynamic - if you have images that represent a dynamic field, such as a personalised name or review score, these will be static and not update - this isn’t great if these fields need to change.

Mobile-First Design

Over 50% of emails are opened on mobile devices, so it’s essential to ensure images look great across different screen sizes. Use responsive designs and test emails on multiple devices to avoid distorted or cropped images. Consider making your text larger and easier to read in consideration of mobile users.

Image Format

Starting off, let’s look at what format you should use when building your emails.

If you want to ensure that your imagery displays on all email clients, you need to use one of the three following image types:

PNG

Extension: .png

PNG files are ideal for high-quality images with sharp lines, text, or transparency. As a 'lossless' format, they retain all data and quality when saved. However, this can lead to larger file sizes, which may slow email loading times. PNGs are especially useful for logos requiring transparent backgrounds, such as those displayed on coloured or dark-mode email designs.

JPEG / JPG

Extension: .jpeg or .jpg

JPEGs (also known as JPGs) are the most common image file type. As a 'lossy' format, they lose some data and quality each time they are saved. However, they remain ideal for photographs and typically load faster in emails than PNGs.

GIF

Extension: .gif

GIFs are used for animations within emails and can be an excellent way to grab customers’ attention. However, they are complex and restricted, so use sparingly – best practice is one GIF per campaign. File size is a concern, as GIFs should not exceed 1MB. Additionally, they have limited colour options, which may result in a grainy effect called 'dither.' Always test campaigns with GIFs thoroughly across multiple devices before sending.

Image File Size

File size significantly affects email performance. Large files can slow loading times and increase the risk of your emails being flagged as spam.

Individual file sizes should not exceed 1MB. Also, limit the number of images in your email to reduce the overall size. Avoid designing entire emails using tools like Photoshop and uploading them as a single image, as this impacts load speed and may trigger spam filters. We recommend aiming for a 60:40 ratio of images to text, ensuring 60% of your content consists of imagery and 40% text.

Image Dimensions

Following best practices for image dimensions helps maintain quality while keeping file sizes manageable. The recommended width for email images is 600px. This ensures your images are clear, high-quality, and optimised for email layouts.

Using images in your designs

When uploading images, there are some considerations to be made.

• Make sure to leave ample space around your images. Cluttered designs can be distracting and harder for customers to scan - space is key!
• Monitor your image to text ratio - you should aim to have a 60:40 image to text ratio - too many images, and likewise too much text, can be distracting and difficult for users to read. 
• Test loading times - send yourself test emails and make sure they load in sufficient time. You might only have a couple of seconds to catch a customer’s attention before they swipe off your email, so you don’t want that to be wasted as images load. It’s good practice to have an internal ‘seed list’ or testing list to send your emails to so you can trial these on multiple devices and email providers.

Accessibility and Alt-Text

Alt text ensures that visually impaired users can still understand your email content using screen readers. It also acts as a fallback if images don’t load, providing context for what the image represents. Keep alt-text concise and descriptive.

Conclusion

By following these best practices, you can create visually appealing, engaging emails that load quickly and avoid spam filters. Remember to prioritise balance and test your campaigns thoroughly across devices to ensure a seamless customer experience.