This article applies to Foxy versions 1.0 and later.
By default, Foxy activates both the HTML and Text versions of the email receipt that gets sent to the customer and the store (depending upon your configuration ― it can be turned off). The text version of the email provides a version of the receipt just in case the customer's email client can't use HTML email. The customer's email client will choose which version to display (in other words, only one version will display to the customer).
If you make customizations to your email receipt templates, you'll want to check to see which versions you need to customize. If you're using both html and text, which is likely, you may want to customize both versions.
If you're unsure of your setting, you can check this in the Foxy admin under the email receipt settings. If the email delivery type option is set to Send Text and HTML E-mail, then you're sending both versions. Otherwise, you're only sending the Text version, and that's the version you'll want to customize.
As always, feel free to reach out to us if you need further clarification.