To add a one-click unsubscribe link to the footer of messages sent to the mailing list:
- Log in to the mailing list admin area under "Email" -> "Mailing Lists".
- Edit your mailing list.
- Go to "[Non-digest options]"
- Set "Should Mailman personalize each non-digest delivery?" to "Yes".
- Add the following to "Footer added to mail sent to regular list members":
Unsubscribe:
%(user_optionsurl)s?password=%(user_password)s&unsub=1&unsubconfirm=1
Note: The above code will send the user's password in clear text, which is not recommended for security reasons. By default a link is already sent in the message footer to the user's control panel from which they can unsubscribe after entering their password.
To ensure that the footer appears in the body of the email instead of an attachment:
- Log in to the mailing list admin area under "Email" -> "Mailing Lists".
- Edit your mailing list.
- Go to "[Content filtering]".
- Set "Should Mailman filter the content of list traffic according to the settings below?" to "Yes".