What is the List-Unsubscribe header? And how can this be implemented in ACS?

Description

What is the List-Unsubscribe header?

The List-Unsubscribe header is an optional email header you can add to your messages. It allows subscribers to see an unsubscribe button they can click if they would like to automatically stop receiving your email.

List-Unsubscribe is used by Gmail, Outlook.com, and others. It is meant to help reduce complaints by giving subscribers a different method to safely unsubscribe without negatively impacting your sending reputation.

The List-Unsubscribe header is easily confused with two other options that subscribers can use to unsubscribe from your email.

The List-Unsubscribe option is not:

  • The spam button: When the junk or spam button is clicked, a complaint is triggered, which negatively impacts your sending reputation.
  • The unsubscribe link within the email creative: This link is usually in the footer of your HTML creative and is controlled by you. However, the List-Unsubscribe functionality is controlled by the mailbox provider, if you have included it in your headers.

In other words, think of the List-Unsubscribe option as a third method for subscribers to get removed from your mailing list. And it’s an option that helps protect your reputation by potentially reducing your complaints.

The List-Unsubscribe email header is defined in RFC 2369.

Resolution

And how can this be implemented in ACS?

On ACS, it’s only possible to add an SMTP header in the delivery template (it can’t be added directly in the delivery).

Here are the steps to follow:

  1. Open and edit the properties of your delivery template

  2. Click on the section SMTP and edit the Headers from Additional SMTP headers

  3. Add the following command line

    List-Unsubscribe: mailto:bounce@subdomain?subject=unsubscribe%=escape(context.mimeMessageId)

    The email address bounce@subdomain represents the returnpath address

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