Steps to enable Email Annotations

Steps to enable Email Annotations

Introduction

In this article, you’ll learn the step-by-step process to enable and implement Gmail Email Annotations, helping you capture attention, boost engagement, and drive more conversions from your campaigns.

Requirements for enabling email annotation

To use Gmail Email Annotations, your brand must first be added to Google’s allowlist, as only approved senders can access this feature. Email annotations enhance your messages by displaying rich details—like deals, product images, and special offers—directly within the Promotions tab on Gmail mobile.

  1. Request Allowlisting
    Email - p-promo-outreach@google.com with your domain(s), subdomains, and landing page URLs. Approval typically takes 7–10 business days.

  2. Add Annotations to Your Email Template
    Insert the relevant code snippet for the annotation type you want to use (deal highlight, carousel, or single image).

  3. Follow Image Guidelines

    • Use high-quality images (over 500 KB) with at least 256×256 px dimensions.

    • Maintain a rectangular aspect ratio.

    • Use the same image for all recipients (avoid unique images per user).

  4. Understand Gmail’s Density Cap
    Gmail limits the number of annotated emails visible in a user’s Promotions tab to prevent clutter.

  5. Test Before Sending
    Note that annotations may not appear in small test sends; they are primarily designed for bulk campaign sends.

  6. Supported Environments
    Annotations are visible only in the Promotions tab on Gmail’s mobile app, not in other tabs or web browsers.

  7. Troubleshooting Tips
    If annotations don’t display, check:

    • Your allowlisting approval status

    • Image quality and size

    • That the email is opened in the Promotions tab

Idea
Note: The code required for implementing Email Annotations is only compatible with custom HTML using code view or hybrid email templates. This functionality cannot be used with AiTrillion's drag-and-drop editor. We recommend using Email Annotations only if you’re technically proficient or have access to a developer who can assist with custom coding. While AiTrillion supports this feature, our support team cannot create or edit custom HTML templates beyond the general guidance provided in this documentation. To ensure the security and privacy of your data, AiTrillion's support team is unable to access or open your HTML files.

Here are the steps to enable email annotation on Gmail:

Step 1: Go to Email marketing >> Templates >> Create from scratch or use the template. (In my case, I am using the template)



Step 2: Click on Code editor
Quote
Note: Email annotation will only work with the Code editor.


Step 3: Add the code as per your needs. Now, there are 3 types of annotation. Copy and paste the code in the head as per your need.
Info
Note: You need to copy and paste the code below of the required annotation in the head section of AiTrillion's HTML editor.


A promotional email that displays a carousel of three image previews of sock deals.
  1. // Build the first image preview in your product carousel:
    <div itemscope itemtype="http://schema.org/PromotionCard">
      <meta itemprop="image" content="IMAGE_URL1"/>
          <meta itemprop="url" content="PROMO_URL1"/>
    
      // Optionally, include the following PromotionCard properties:
      <meta itemprop="headline" content="HEADLINE1"/>
          <meta itemprop="price" content="PRICE1"/>
          <meta itemprop="priceCurrency" content="PRICE_CURRENCY1"/>
          <meta itemprop="discountValue" content="DISCOUNT_VALUE1"/>
          <meta itemprop="position" content="POSITION"/>
        </div>

    // Build the second image preview in your product carousel:
    <div itemscope itemtype="http://schema.org/PromotionCard">
      <meta itemprop="image" content="IMAGE_URL2"/>
          <meta itemprop="url" content="PROMO_URL2"/>
    
      // Optionally, include the following PromotionCard properties:
      <meta itemprop="headline" content="HEADLINE2"/>
          <meta itemprop="price" content="PRICE2"/>
          <meta itemprop="priceCurrency" content="PRICE_CURRENCY2"/>
          <meta itemprop="discountValue" content="DISCOUNT_VALUE2"/>
          <meta itemprop="position" content="POSITION"/>
        </div>

    // To include more image previews, add additional PromotionCard objects.
    // You can include up to 10 image previews in a product carousel.

2.) Single image preview

  1. 
    // Build the first image preview in your product carousel:
    <div itemscope itemtype="http://schema.org/PromotionCard">
      <meta itemprop="image" content="IMAGE_URL"/>
          <meta itemprop="url" content="PROMO_URL"/>
    
      // Optionally, include the following PromotionCard properties:
      <meta itemprop="headline" content="HEADLINE"/>
          <meta itemprop="price" content="PRICE"/>
          <meta itemprop="priceCurrency" content="PRICE_CURRENCY"/>
          <meta itemprop="discountValue" content="DISCOUNT_VALUE"/>
        </div>


3.) Deal/Offers


  1. 
    <div itemscope itemtype="http://schema.org/DiscountOffer">
      <meta itemprop="description" content="DESCRIPTION"/>
          <meta itemprop="discountCode" content="DISCOUNT_CODE"/>
          <meta itemprop="availabilityStarts" content="START_DATE_TIME"/>
          <meta itemprop="availabilityEnds" content="END_DATE_TIME"/>
        </div>


Step 4: Once everything is done, click Save & exit.





Idea
Note: In some cases, Google may automatically extract information from your emails to create annotations — even if you haven’t added the annotation code manually. This process is entirely managed by Google and cannot be controlled or guaranteed by the sender.

Email Annotations Troubleshooting

Google enforces strict standards for displaying annotations, and they may not appear for various reasons. If your annotations aren’t visible after completing the setup steps, review the troubleshooting tips below:

1. Verify Your Brand Is Allowlisted

Google only permits approved brands to use email annotations to maintain security and prevent spam. If your brand isn’t on the allowlist, you’ll need to request access directly from Google.

To request allowlisting:

  • Contact Google using the instructions provided above.

  • Wait approximately 7–10 business days for a response.

  • Note that approval is not guaranteed — Google makes the final decision at its sole discretion.

2. Check Image Quality

All annotation images must meet Google’s visual quality standards. Low-quality or improperly formatted images will be filtered out and won’t appear in the Promotions tab.

Ensure your images meet the following criteria:

  • High quality (generally larger than 500 KB)

  • Minimal or no overlaid text

  • Rectangular shape — avoid circular or masked images

  • Minimum size of 256 × 256 pixels

  • The same image must be used for all recipients

Avoid using tools that generate CID (Content-ID) or per-recipient images, as Gmail will block annotations in those cases.

3. Consider Gmail’s Density Cap

Gmail limits the number of annotation images displayed in a user’s inbox at one time (known as a density cap). If the Promotions tab already contains several recent annotated emails, Gmail may suppress additional ones to avoid clutter. This limit is automatically enforced by Google and cannot be overridden.

4. Preview Sends May Not Show Annotations

Annotations often don’t appear in test or preview emails sent to a small number of recipients. This feature is intended for bulk sends — annotations are more likely to display when the campaign is sent to 100+ recipients.

5. Confirm You’re Checking the Supported Gmail Tab

Annotations only appear in the Promotions tab of the Gmail mobile app. They will not display in:

  • Any other Gmail tab (e.g., Primary, Updates, or Social)

  • Gmail accessed through web browsers (mobile or desktop)

  • Inboxes of users who have disabled the Promotions tab in their settings

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