Email annotations provide a way for marketers to make promotional emails stand out in the Gmail mobile app by displaying key information in the Promotions tab before recipients even open the email. With these annotations, you can highlight special offers (like coupon codes), show product images, and create engaging carousels—all in the inbox preview.

This guide covers everything you need to know about setting up Gmail annotations, including recommended prerequisites and code snippets.

Requirements and limitations of email annotations

• To use annotations, your brand must be on Google’s allowlist. Submit an application via email to [email protected], including information about your domains, subdomains, landing pages, and other relevant details. Allowlisting typically takes 7-10 business days, and NotifyVisitors does not have influence over Google’s decision or processing time.
• Annotations are ideal for marketers familiar with HTML or who have access to a developer. NotifyVisitors supports the feature but cannot directly assist in building custom annotation code templates.
• To add email annotations code, you can only use html based editor or AMP email editor of NotifyVisitors. Email annotations can not be applied in emails designed in drag and drop editor.

Types of Gmail annotations

Annotations only appear in the Promotions tab of Gmail’s mobile app, which means they won’t show up in other Gmail tabs or on desktop views. Gmail currently offers three types of annotations:

• Deal/Offer annotation: Display a promotional offer, such as a discount code or free shipping, and specify the expiration date.

• Product carousel annotation: Add a rotating carousel of images to showcase multiple products, including optional details like name and price.

• Single image annotation: Feature one product image and any supporting details to highlight a specific item.

Annotation code implementation

Here’s how to set up each annotation type in your HTML email templates:

Deal/Offer annotation

Replace the placeholders with a short description of the deal, the discount code, and the start and end times in ISO 8601 format.

Product carousel annotation

Add up to 10 items to your carousel by including additional PromotionCard sections, and be sure all images are in the same aspect ratio (4:5, 1:1, or 1.91:1).

Single image annotation

Troubleshooting email annotations

If annotations don’t appear as expected, check the following:

• Allowlist status: Ensure your brand has completed the allowlisting process.
• Image quality: Use high-resolution images (minimum 256x256 pixels) without text overlays.
• Gmail density cap: Gmail limits the number of annotated emails in the inbox, so recipients may not see all your annotations if their Promotions tab is full.

Sending test email

Sending a test email to just one or two people usually won't trigger annotations in the inbox. Annotations are specifically designed for bulk emails, so they typically show up only when a message is sent to more than 100 recipients. To effectively test this feature, it's best to create a test segment with over 100 recipients.

Another option is to utilize Google’s promo tab preview tool for developers. This tool lets you test your code and view how annotations will look to recipients.

Conclusion

Ready to make your emails pop in Gmail? With these annotations, you can turn email previews into powerful brand moments and engage recipients at first glance. For further assistance or custom solutions, NotifyVisitors is here to support your goals.