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Last updated on Aug 27, 2026
The HTML email editor lets you brand the messages Advanced Billing sends on your behalf, so a receipt or a renewal reminder looks like it came from you rather than from a generic billing system. You write the structure and CSS once as a layout, then assign that layout to as many templates as you like. Editing layouts and templates requires the Setup permission.
Two pieces combine to produce each email, and knowing which is which saves a lot of confusion:
To edit either, you'll need a working knowledge of HTML. Advanced Billing also supports Markdown in the email body, which is an easier way to produce decent-looking content without writing markup by hand.
Important: Existing emails keep sending exactly as they did until you assign a custom layout to their template.
To create a layout
Important: A layout must contain the
{{ main_content }}tag. That tag marks where the template's own content is inserted, and Advanced Billing rejects any layout saved without it.
The layout previews live as you edit, in the right-hand pane, so you can see the effect of a change without saving. Previewing works once the layout has been saved for the first time.
To return to the template you came from, click the < Email link in the top left of the editor.
Fonts belong to the layout rather than to an individual email, so defining one in a layout changes the font for every template assigned to it. The example below sets the default font to Arial. Adjust it to your own preferences.
<!DOCTYPE html>
<html>
<head>
<style>
p {
font-family: arial;
}
</style>
</head>
<body>
<p>
{{ main_content }}
</p>
</body>
</html>Select the layout from the layouts drop-down and click Save. The template then renders inside it. The drop-down's first option is None, which sends the template without a custom layout.
To change a layout later, select it from the drop-down and click the pencil icon. The pencil appears only when a layout is assigned.
Nearly every email Advanced Billing sends can be edited this way, including Sign-up, Customer Receipt, Card Expiration, End of Trial, Cancellation, Update Payment Request, Term Renewal, the ACH and direct debit notices, the prepaid subscription notices, dunning, the invoice and proforma invoice notices, and the Portal invitation. Which of these appear depends on the features your site uses.
Important: Upcoming Invoice is the one exception. It has no editor, so you can't assign it a custom layout.
WARNING: Maxio Support can't debug the HTML in your templates or layouts. Test your markup before applying it to a live site.
These requirements apply to layouts, not to template bodies. Layouts are validated as strict, well-formed XML rather than ordinary HTML, so markup a browser would happily accept can still be rejected. Template bodies aren't validated this way, which is why a bare <br> is fine in a template but breaks a layout.
Make the following changes to valid HTML before pasting it into a layout:
<img ... />.<br />.<!-- abc -->.{{ main_content }} tag, so the template's content has somewhere to go.If you see the alert HTML is invalid. Missing a closing tag? Error at line: 247 position: 5879, an unclosed tag is the usual cause. The line and position in the message point at where the parser gave up. A bare <br> is the most common culprit, so replace it with <br />.
The template holds the content of one specific email, and it's where you write the wording your subscribers read.
Editing a template works the same way as editing a layout, with Liquid variables available in the body. Pause for a second or two after typing and the preview pane on the right updates. For the full set of variables you can use, see the Customize Email Templates help article, which the editor also links to directly under the Subject field.
Changes don't affect emails being sent until you click Save.
The editor renders your template against sample values, so you can set up a condition and see how it resolves before anything reaches a subscriber. To change those sample values, see the Preview Emails with Test Data help article.
Still need help?
Reach out and our support team will take it from here.