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Optimizing load time of your emails
Optimizing load time of your emails

Learn how to improve your emails' loading speed

Ira avatar
Written by Ira
Updated over a week ago

There are many aspects email marketers should consider to optimize their email marketing. Spam traps, sender reputation, contact list hygiene, email content, and subject lines are all factors. However, email size and loading speed are typically overlooked. The size and speed of your email affect your brand's marketing perception.

Adding CSS animation, responsively showing/hiding images or content, complex media queries, and other new effects are adding a lot of weight to emails.

Limit the number of images

Each image you load is a separate request to the server. If you load 20 small images, that's 20 requests, which makes your emails load longer. The email's loaded weight is how big it is when a user opens it in the email client. This includes all the downloaded images.

The best way to use images in your newsletter is to keep your emails consistent. Optimizing the ratio of images to text is one of the easiest ways to speed up load time and improve performance across all metrics. Although there isn't definitive evidence that having a good text-to-image ratio always helps, it's still likely that it could favor how well your emails perform. A sentence or two of text should be included to balance each image you have.

Styled text, Unicode letters, CSS triangles, etc., can often be used to replace images.

Optimize Images

  • Save images for WEB. It's possible to reduce the file image file without significantly reducing the quality of your images. The best way is to use the "Save for Web" function that most Image editors have.

  • Always export the web version of your images with a max of 72 DPI. To find out an image's DPI in Windows, right-click on the file name and select Properties → Details. In the Image section, you'll see the DPI, labeled Horizontal Resolution and Vertical Resolution. On a Mac, you need to open the image, and select Tools → Adjust Size in the menu bar. This will fix problems with blurriness and keep your pictures looking sharp.

  • If you download a stock photo for your email, make sure you open it in an image editor and resave in desired quality.

  • Mobile devices won't automatically resize side-by-side images if their height and width don't match. Keeping your images uniform and sized correctly will prevent mobile image stacking issues.

  • Choose the proper format for different images.

    – JPG for photographs,
    – PNG-8 for simple images,
    – PNG-24 for images and photographic elements combined.

  • The highest quality is maintained in a PNG file. Because of this, a PNG will also make your email bigger overall. Keeping the image sizes small and running your images through an optimization application will reduce the overall size of the image while maintaining the quality you want.

  • Use 3rd party apps for Image optimization to further optimize images for the web. Poorly optimized images increase load time and take up precious bandwidth from both users and networks alike.

Break a lengthy email

Instead of having a lengthy email containing a lot of content, break a long email into numerous different sections with dividers (Line/Space block). This allows the browser or email client to start laying out the email from top to bottom.

It also means that most email clients can start rendering your information sequentially from top to bottom, giving the impression that your email is loading more quickly.

As opposed to adding independent, stacked blocks with no dividers increases the overall size of the email markup.

Keep the email short

As simple as it is. Include less information, and the size of your email will automatically decrease. Moreover, this appears to be a growing pattern, and research has shown that emails with a single, straightforward message perform better. Without a lot of text in your email, strategically placed links can encourage the reader to click to find out more information and, as a result, purchase your product.

📰 Short emails are also less intimidating for non-readers who may be overwhelmed by multiple paragraphs.

Minify HTML

This one is for customers who are experienced in coding and use HTML in their emails. Minification is the process of minimizing code in your emails. If you use HTML templates, HTML content block, or any CSS codes - It's one of the main methods to reduce load time. Minifying can significantly reduce the HTML size. Along with minifying HTML, you can also minify your CSS code used in email. Minified email code weighs less in KB, making it easier to send, more accessible to open, and saves mobile data on plans with limited bandwidth. It also lowers the chance of Gmail clipping. Every bit helps! This also means cropping unwanted white space. Using HTML to position the image instead of white space can easily reduce an image file size.

🎨Tip for designers! "Time to Display" or "Time to Paint" is the essential point for email designers to consider. This is how long it takes for the email client to show the email's content. And as email evolves and uses more CSS, both the browser and the email client have to push extra to display the HTML. That's the metric that email designers should really care about.

Mobile usage

Download speed on mobile devices is significantly lower compared to those of desktop browsers and applications. The performance will be a more significant issue if you have a large mobile audience. It should influence your design selections in terms of the number of images and file sizes correspondingly.

Remember that customers on the go are likely to skim your emails, so make sure your content is clear and concise. That's why we advise using visibility settings in your emails to have less bloated content shown for mobile devices.

To limit the visibility, click on the content block you'd like to change the visibility for and choose the Layout tab. Scroll down to Display settings -> Choose which devices should show the content block selected. You can show it to:

  • all devices;

  • mobile devices only;

  • desktop devices only.


As long as you take these recommendations into account and adhere to best practices when crafting your newsletter to ensure it is not image-heavy, the platform and emails will perform to their fullest potential. You can check how well emails with these tips work by applying them to a single email and using the A/B content test. Apply these tips to your following email and check the results!

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