> ## Documentation Index
> Fetch the complete documentation index at: https://dev.smile.io/llms.txt
> Use this file to discover all available pages before exploring further.

# Overview

Smile's email notification system allows you to build customized HTML email templates with the help of [handlebar](https://handlebarsjs.com/expressions.html) variables. You can personalize your emails to make them more valuable and ensure your customers continue to open them. Not familiar with handlebar variables? [Learn more about how they work](https://handlebarsjs.com/expressions.html).

<Warning>
  Custom HTML email functionality is deprecated and no longer generally available. This document is maintained as a reference only.
  For merchants that want to send fully custom loyalty program emails, we recommend using our Klaviyo integration.
</Warning>

Refer to the list of available [handlebar variables](/guides/deprecated/custom-html-emails/custom-email-variables) and [objects](/guides/deprecated/custom-html-emails/custom-email-objects) as well as the [example emails](/guides/deprecated/custom-html-emails/custom-email-examples) to get started!