CiviMail: unsubscribe message shouldn't suggest a re-subscribe action to non-public groups

If a contact is on a private group and sends an unsubscribe request, they will receive a confirmation message with a link to re-subscribe. The re-subscribe email will be processed as a failure however since the group is not public.

Solutions that I can think of ranked in order of quality:

a) The full solution to have hash re-subscribes that work for both public and private groups. This is described here http://issues.civicrm.org/jira/browse/CRM-1799 but is not slated until 2.0.

b) Not process re-subscribe links in the unsubscribe replies for private groups.

c) Mention in the documentation or interface that the message templates for private groups should not contain re-subscribe links.