While it is often overlooked, email size plays a crucial role in delivering a message to your audience. It can also affect how your campaign renders across different email clients. Thus, it is very important not to surpass the recommended email size for reasons what we will highlight in this article.

Email size affects deliverability

The purpose of sending an email campaign is to reach an audience with a very specific message. The intention of email marketing is to reach a broad audience composed of potential or current customers; whether that is to inform, promote or solicit sales.  As the person sending the message, you may have designed a very fancy creative, selected all the best words and have the most compelling call-to-action. However, if your email size is greater than 100k, all those efforts may simply go to waste.

Loading time

According to multiple sources, including Email on Acid, email size should not to exceed 100k. The larger the email size, the longer it will take for all contents to download. As explained by CheetahMail, on a 56k modem, it takes 2 seconds to download 10k. Therefore, a 30k email will be downloaded in 6 seconds, a 60k will take 12 seconds and so on.

The longer the loading time, the more likely the email will be deleted. Given that users are bombarded with emails daily, the likelihood of them hanging around waiting for your email to load is highly unlikely. This gets even more improbable if a user is viewing their email on a mobile device, using their cellphone data. This last scenario may end up in your email being deleted due to the following factors:

  • Large images eat up precious megabytes in limited data plans
  • Download speed over cellular data can be much slower.

That being said, if the size of your email campaign is too big, chances are that your email will end up in the Trash can! Given that 20-50% of people are now using a mobile platform to check their email, it is advisable to design email templates that accommodate to mobile devices, limited data plans, and slow networks.

In sum, if your email campaign size is under 100k, the smaller the size, the quicker it will load and the more likely that your user will take the time to look at it.


Your inbox won’t filter emails smaller than 100k. But if your message exceeds 100k, it will be clipped.  In the case of Gmail and Gmail for IOS, things get a little different. Instead of getting the original email blast, when an email size exceeds 102Kb, Gmail displays only the first 102K and cuts off the remainder.  Google then provides a link at the bottom of the message, which will redirect the user to preview the full message in a brand-new tab.

Email size Matters: clipping

When the email size is greater than 102k, Gmail clips the message and it will look like this picture.

Gmail for Android and iPad

Moreover, both Android and iPad versions of Gmail cut off the message and replace it with “…”. This can be misleading and, unless you know that the “…” hide a message, there is no reason to know one must click there.

Email size matters - clipping on mobile

The “…” have are highlighted here.

This clipping feature is turned on for every single Gmail user by default and unfortunately cannot be disabled. This can be frustrating, not only for you as an email marketer, but also for the user.

Thus, this can be detrimental as all your audience members who use Gmail products (whether that is a private email account, Gmail for IOS and Android, or a corporate email account powered by Gmail) won’t necessarily receive your intended campaign in its full glory. If the call-to-action is not available in the unclipped section, your email campaign may be a waste of time. Always keep this in mind:

If the reader has to take any extra step to read your message, this can become a massive stumbling block in the success of your email campaign. 

Moreover, our friends at Email on Acid have ran tests that outline the behaviour of spam filters triggered by email size. Here is a breakdown of deliverability issues based on email size:

Email size matters - spam filters triggered by email size

Best practices on email size – Is there a fix?

You bet there is a fix! You can save some bytes to ensure that your email size does not exceed that dreaded 100k mark.  Here is how:

Keep your email content to 20,500 characters (20k) or less.

  • Less is always more!

Remove any unnecessary spaces, carriage returns or comments.

  • This include: <br/> and &nbsp;

Double-check for redundant in-line styling

  • Using styles again and again for specific elements is not a good practice. It’s very important for you to clean your code and remove redundant styles. For example, if you have a paragraph tag <p> and span tag <span> with the same font size and color, you might just group them using a comma:

email size matters : redundant styles

Declare image width and height

  • If you do so, your email design will maintain its structure when images are turned off by email clients. If you only know one of the dimensions, you can set the missing one to “auto”, and that will suffice.

Optimize image size

  • Make your image file sizes as small as possible without losing their visual integrity. This will prevent long email load times. Remember that it is best practice to have your email campaign width to be between 600px- 700px. So, if the width of your campaign is 600px and you have full-width images, you can set all your images to be 600px wide. This will ensure that they render property and you are not using extra large images, which may take much longer to load.

Images count more than their character count

  • By about 170 characters more, to be precise. Again, more is always less.

Have an even balance of text and images in your email template

  • Images are crucial if you want to convey a strong message. Thus, having good images can make your email campaigns look even more appealing and vivid. Know the goals of your email campaigns and identify the results you wish to achieve. This will enable you to find the right balance between written content and the image you decide to feature.  The success of an email campaign truly depends on the well-managed balance of both image and text.
  • Keep in mind: If an email campaign is text-heavy, this may overwhelm your readers. If you loose their attention, your message may not even get across.

Avoid using one large image as your entire email, or too many images in general

  • An email campaign that contains a lot of images and poor written content can look incredible but will be blocked by many Spam filters. This will cause open rates to decrease. Therefore, the best solution is to design your message with image blocking in mind, considering how your campaign will look if all the images are blocked.

Landing pages For The Win!

  • If you still have too many images and too much information to convey in one message, consider making a landing page. Then, you can direct your users without eliminating any content and you won’t have to fit everything into an email!

Email size matters, period.  Don’t let anyone tell you otherwise.

Contact us if any questions arise. Remember that our Customer Success team is here to help!