Emails sent from the control panel are sent with an 'unsubscribe' link at the bottom of the email. The user can click to unsubscribe or change account settings from an email message that is sent from 'send email' from your site.
Sending an email can be completed under Utilities Send Email
Create the eMail Message
Enter the subject and body information for the email message.
The email message will automatically include the unsubscribe link at the bottom of the email message.