In the email body, highlight the text you'd like to link to your the opt-out page, then click the link iconlink in the formatting bar.
Click the Link to dropdown menu, then select Email subscription link.
Click the Subscription type dropdown menu, then select Subscription preferences.
When recipients click the link, they'll be directed to a page where they can update their email communication preferences.
Please note: Due to the way the unsubscribe link works in tandem with contact identity tracking, you will not be able to fully verify that the link works in a preview of the email. if you want to test out the unsubscribe link, you can send a test email to yourself, then click the link in the test email you receive.