Understanding CSS optimization

Last updated at:

You will learn

Learn about CSS optimization, which is one way you can make sure your emails are not getting clipped in the inbox. 

Why CSS optimization matters

Ensuring your emails hit the inbox matters immensely for the success of your email marketing. Likewise, ensuring that your emails aren’t clipped is crucial for customers to get all the information in your messages. CSS optimization is one of the many tools you can use to avoid clipping. 

About CSS optimization in Klaviyo

When you build emails in your account, Klaviyo uses something called embedded styles in order to add in the branding that you select in the Styles and Block tabs.

Do inbox providers allow for embedded styles? 

By using these to customize your emails, your branded emails have the smallest file size possible to keep them from getting clipped. The largest inbox providers (Gmail, Yahoo, Apple, Outlook, AOL) all accept and render embedded styles.

Smaller inbox providers do not render embedded styles. If you find a large number of your customers are using the inbox providers below or another provider that does not render embedded styles, consider unchecking the CSS Optimization box so your emails look as you designed them.


Common Inbox Providers that Do Not Support Embedded Styles

 Australia telstra.com.au, telstra.com,  bigpond.net.au, bigpond.com
 Russia mail.ru
 Germany/EU gmx.com, t-online.de
Brazil  bol.com

Turn off CSS optimization (and embedded styles) 

Know that if turn off embedded styles, you run the risk of your emails being clipped in other inbox providers, so test your emails before you send them.

  1. Select your organization name in the bottom left corner.
  2. Click Settings.
  3. Select the Email tab.
    Email tab in your account's settings
  4. Uncheck the box labeled Enable embedded styles.
  5. Click Update Email Sending Settings.
    CSS optimization section showing the box to use embedded styles

Additional resources

Was this article helpful?
31 out of 43 found this helpful