All mailings you send using the Mailman mailing list software built into your control panel should contain a one-click unsubscribe link, to comply with the CAN-SPAM act, and to allow us to unsubscribe a recipient who decides to report the email as spam rather than unsubscribe.
Adding a one-click unsubscribe link to your MailMan list is not very difficult.
1. Log into your cPanel and click the "Mailing Lists" icon.
2. Click the "Modify" link next to a mailing list.
3. Enter your password and log into the Mailman admin interface.
4. Click the "Non-digest options" link under Configuration Categories at the top left side of the page.
5. Set the "Should Mailman personalize each non-digest delivery?" option to Yes.
6. Add the following link to the footer: %(user_optionsurl)s?password=%(user_password)s&unsub=1&unsubconfirm=1
For example, to show a sentence at the bottom of the email which reads "Click here to unsubscribe", enter this at the bottom of the footer:
Click here to unsubscribe