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Custom HTML templates

If you want a fully custom design for your newsletter that goes beyond what our built-in layouts offer, you can use a custom HTML template. This...

If you want a fully custom design for your newsletter that goes beyond what our built-in layouts offer, you can use a custom HTML template. This article covers when to consider one, how they work, and where to manage them.

When to use a custom HTML template

Custom HTML templates are best for:

  • Highly branded designs that built-in layouts can't quite achieve
  • Complex layouts with specific element placement
  • Brand consistency across email and web
  • Sophisticated visual treatments beyond plug-and-play templates

If you can achieve your design with one of our built-in layouts, do that — it's much simpler and easier to maintain. Custom HTML is more powerful but requires HTML knowledge to maintain.

Audience: HTML knowledge required

Custom HTML templates assume you (or someone on your team) can read and edit HTML. If you don't have that skill in-house:

How custom HTML templates work

Custom HTML uses rasa.io tags to insert dynamic content at send time. For example, an article block looks like:

When the newsletter generates, rasa.io replaces these tags with the actual article title, description, and image — personalized per subscriber.

Where to manage custom HTML templates

Custom HTML templates live in Content → Layouts. Here you can:

  • Upload a new HTML template
  • Edit an existing template in the dashboard's HTML editor
  • See a live preview as you edit
  • Save changes (or save as a new copy to preserve the original)

To assign a custom template to a newsletter, go to Messaging → [Your Newsletter] → Email tab → Template → Change and pick the template.

Available rasa.io tag modules

For a reference of all the available rasa.io tag modules you can use in your custom HTML, go to Settings → Custom Email Templates. This page lists each module with copyable code blocks. Common modules include:

  • Article Display — show an article with image, title, and excerpt
  • Header Content — newsletter header
  • Footer Content — newsletter footer
  • Sponsor Content — ad or sponsored placement
  • Section — group of articles
  • Banner image, Square image, Text/HTML block

Copy the tag you need and paste it into your HTML where you want the content to appear.

Important rules

**Don't remove data-rasa-* attributes** unless you know exactly what they do. These attributes tell rasa.io how to insert dynamic content. Removing them breaks personalization.

Test before publishing. After editing, send a test to yourself. Open in multiple email clients (Gmail, Outlook, Apple Mail) and devices (desktop, mobile).

Use the HTML editor's preview pane. As you edit, the preview shows how the template will render. If a change doesn't appear in the preview, something went wrong — undo with Ctrl+Z (or Cmd+Z on Mac) and try again.

Editing safely

If you're making changes you're not sure about:

  • Use Save as new copy to create a duplicate template you can test
  • Keep the original template assigned to your newsletter until you've validated the new one
  • Once you're happy with the new version, switch your newsletter to use it

Common safe edits

Even without deep HTML expertise, you can safely:

  • Update text content (headers, intros, footer messages)
  • Change company address and contact info
  • Swap social media links
  • Update color values (look for color: and background-color: in the HTML)

Riskier edits (best done with HTML experience):

  • Restructuring layout
  • Removing or rearranging modules
  • Modifying email-safe CSS

What's next

  • Templates and design (Layouts) — the broader overview
  • Adding your own text, images, or advertisements — scheduled content basics
  • Sending test emails and previewing — testing your custom template