How to Add External Promotions Using the HTML Block

When Should You Use This?

The HTML block in Letterhead allows you to embed custom HTML code directly into your newsletter. This is particularly useful if you’re working with third-party advertising platforms or need to insert personalized code snippets.

In this article, we’ll walk you through how to use the HTML block effectively—including how to handle merge tags, when ads will display properly, and tips for testing.

---

How to Insert a Promotion with the HTML Block

1. Go to your Newsletters section in Letterhead.
   

2. Start editing a newsletter or create a new one (either from a template or a blank layout).

   

3. On the right-hand panel, find the HTML block.

   

4. Drag it into the newsletter where you want the promotion to appear.

   

5. On the right side, paste your HTML code.

   

Step-by-Step: How to Use It

1. Obtain your code
   You’ll typically receive HTML code from a third-party platform (e.g., an ad server or campaign manager). This code may contain placeholder merge tags (like {EMAIL}, {FIRST_NAME} etc.).

2. Add it to Letterhead
   Drag the HTML block into your newsletter and paste your code into the block.

   

3. Replace the merge tags
   Replace any placeholder merge tags in the code with Letterhead’s supported personalization merge tags. This is critical so the variables work properly when the email is sent.

   Placeholder	Replace with
   {EMAIL}	{subscriber.email}
   {FIRST_NAME}	{subscriber.first_name}
   {LAST_NAME}	{subscriber.last_name}

4. Enable Relaxed HTML
   Make sure the “Relaxed HTML” option is turned on, so the code renders correctly.

   

Important Notes About Testing Ads

If you’re using the HTML block for an ad (especially third-party ads), be aware that test emails will not display the ad correctly. This is because the ad system depends on a fully published email with an actual recipient address to activate and track the impression.

Why does this happen?

When you send a test email, it’s not recognized as a live send. Since the system doesn’t associate a real subscriber with a test, the ad platform won’t populate the ad. However, when you publish and send the real newsletter, the ad will appear as expected.

Can I Personalize These Promotions?

Yes. You can include merge tags in your HTML to dynamically insert subscriber info.