Autoresponder messages cannot have links that contain any personal user session information, such as unsubscribe links.  An autoresponder is essentially a "receipt" of an action performed by the user and you cannot unsubscribe from it. As it is a form of receipt, it is not considered a part of the Congressional CAN-SPAM Act.

To see if the "Autoresponder Messages" option is enabled in your stationery, go to Email and click Stationery. Find the stationery that is being used in your message and click edit. Look at number 3 on this page, "Which applications should be allowed to use this Stationery" and notice there is a checkmark for Autoresponder Messages. If one of these types of links are in an autoresponder, they will be cut from the content at time of send and possibly affect the layout of the email.

You can add a link to the constituents profile, if you like that can give the constituents an opportunity to opt out of email:
  1. Find and edit the autoresponder or stationary for the autoresponder.
  2. In the WYSIWYG highlight the desired text, e.g. "Click here to change your preferences,"
  3. Click on the chain link icon to create a link.
  4. Click Browse Links.
  5. Select User Registration on the left.
  6. Click Update Profile.
  7. Click Select.
  8. Click Insert.