How to Set Up List-Unsubscribe Headers in Mailmodo

In 2024, Google and Yahoo updated their bulk email sender guidelines, emphasizing the importance of the List-Unsubscribe header.

This hidden email header allows inbox providers to display a native one-click “Unsubscribe” button. Without it, your emails are more likely to hit spam folders, and users are also more likely to mark you as spam .

Let’s further explore what it does and how to set it up correctly.

What is a list-unsubscribe header?

The List-Unsubscribe header is a hidden line of code inserted into the email header (not the visible content) that tells inbox providers where to send unsubscribe requests. It typically looks something like this:

List-Unsubscribe: mailto:unsubscribe@yourdomain.com, https://yourdomain.com/unsubscribe

When this is correctly implemented, Gmail, Outlook, and other inbox providers can render a native "Unsubscribe" button in the UI — improving the user experience and reducing spam complaints.

How to implement the list-unsubscribe header

In most email marketing systems or custom SMTP setups, you have to manually write a line of code in the email header, like:

List-Unsubscribe: mailto:unsubscribe@example.com, https://example.com/unsubscribe

You need to format it correctly using angle brackets and ensure the URLs are accessible. This allows email clients to include an unsubscribe hyperlink in the header of the email to your recipients.

But when you’re sending campaigns through Mailmodo, you don’t have to do any of this manually.

Mailmodo automatically adds the List-Unsubscribe header to every email sent through its platform. It’s part of the backend configuration — meaning no code, no setup, no syntax errors to worry about.

Why the unsubscribe button might still not render

Even though you’ve included the header, inbox providers don’t always show the “Unsubscribe” button. Here's why that might happen:

• Low sender reputation: Gmail and Outlook reserve this UI feature for high-reputation senders only.

• Test emails: The button typically doesn’t appear in emails sent to yourself or teammates for testing.

• Improper header format (on other platforms): If you’re switching from a different tool, be aware that incorrect formatting (like missing angle brackets) can make the header invalid.

• Client-specific behavior: Each inbox provider uses its own rules. Gmail might skip rendering the button if it doesn’t fully trust the sender.

So what’s the solution to this?

Add a custom unsubscribe link in the email body

As a best practice, it’s smart to include a visible unsubscribe link inside your email content — especially in the footer. This gives recipients a clear opt-out path, even if the ESP doesn’t render the native unsubscribe UI.

How to do this in Mailmodo:

1. Use the footer block in pre-built templates or new templates. If you’re using a Mailmodo pre-built template or creating a new one, the footer block typically includes an unsubscribe link. You can set it up by linking anchor text (like “Unsubscribe”) to your unsubscribe URL.

2. Add a custom unsubscribe link if needed. You can place an unsubscribe link anywhere in the email using Mailmodo’s personalization tag {{unsubscribe_url}}. This can be inline, at the top, or in a custom footer.

3. Send a test email to make sure the link:

• Appears clearly

• Leads to a functioning opt-out page

• Matches your email type settings (e.g., promotional or newsletter), so Mailmodo tracks unsubscribes correctly

Final thoughts

Managing unsubscribe headers and email compliance doesn’t need to be complicated or technical. With Mailmodo, everything is handled for you behind the scenes — from adding the List-Unsubscribe header to managing suppression lists and opt-out preferences. You can focus on creating great campaigns while Mailmodo takes care of the deliverability and compliance details.

If you're looking for a simpler, smarter way to send emails that respect user preferences and inbox rules, give Mailmodo a try. It’s built to help marketers send better emails — without the code or complexity.

Try Mailmodo today and see how effortless email compliance can be.