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How do HTML Size, Image Size, and Pixel Height Impact Email Previews

N.Makarov
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Sometimes the HTML size, image size, or pixel height can cause issues with your Email Previews. These impact the time it takes for your email to load, and in return, Mailjet is unable to get a true snapshot of your email. You may see distorted images, partial preview returns, or no previews returned. This also means the email will take more time to load than most of your readers are willing to wait, and you may lose engagement in your campaign.

 

HTML Size

Best practice is to keep your HTML size below 102KB. If your email size goes above this, you may begin to see issues with the speed your email is loading, and this could cause Mailjet to return no previews for your test. 

If your email exceeds 102KB for example, Gmail will display the first 102KB and then it will clip off the remainder with a few different variations depending on the device.

 

  • Web Version
    In the web version, Gmail will display a message that reads:
    "[Message clipped] View entire message"
    Clicking on the link will open your email in a new window.
  • Android
    In the mobile version of Gmail for Android – your email will just get cut off with the proverbial “…” Unfortunately there is no link for viewing the entire message.
  • iPhone
    In the mobile version of Gmail for the iPhone, you will see a message at the bottom of your email stating:
    [Message clipped] Download entire message
    After clicking on that link, it will re-open the email but you’ll have to scroll all the way back down to the place where you left off. Even after scrolling all the way back down to the bottom, my test email was not displayed in its entirety.  Instead, it was left with more dots “…” and no link to view more.
  • iPad
    The mobile version of Gmail for the iPad does not appear to offer any links for viewing the entire message, instead, the email is simply cut off.
    In my initial testing, my HTML document did not contain any images, it consisted of mostly text with very little HTML coding.  I also tried this test with embedded images and concluded that since the images are not considered part of the original HTML content itself, they were not clipped nor did they affect the message of my email.  Instead, they were downloaded as one might expect after clicking on the “Show Images” link.
  • So what’s the fix?
    If you are close to 102KB, you might save a few bytes by removing any unnecessary spaces, carriage returns or comments.

 

Image Size

Even though the suggested image size in your email editor is less than 1MB, we recommend that you stay below 200KB, as any overage can cause deliverability and display issues.

mceclip1.png

If the image you are trying to upload exceeds 1MB, you will receive a warning message asking you to optimize the image size. 

mceclip0.png

 

Pixel Height

Best practice is to limit pixel height of the entire email to no larger than 5000 to 7000 pixels. Most web clients have pixel height limit of 7000, and some desktop and mobile clients have a pixel height limit of 5000. If an email is longer than this, it may get cut off at the footer or disclaimer. It could also render fully, but take an extended time to load, hurting reader engagement.

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