How do I Add a List-Unsubscribe Header to an Email?

What is a List-Unsubscribe Header in an email?

A List-Unsubscribe header in an email provides a way for recipients to easily opt-out of receiving future emails from a mailing list. It's a standard header that most email service providers include in outgoing email messages that directs email clients, like Gmail or Yahoo, to add an "Unsubscribe" link or button within the email interface, rather than requiring the recipient to search for an unsubscribe link within the email content.

When you send email from Delivra, our system is setup to automatically add a list-unsubscribe header to your outgoing campaigns.

To check this, you can send an email to your Gmail account from our system (or check a previous received email from the system).

Once opened, click the drop down next to the recipient name: (it will say "show details" if hovered over).

Note the unsubscribe option that is linked:

We don't recommend actually unsubscribing from your own mailing list unless you are using a purely test email address.