Adding "Unsubscribe" to emails

The messages sent by Elgg do not contain any disclaimer, contact details or "unsubscribe links". This is sure to cause problems so I have two questions.

1. How do I edit these messages.

2. Is there anything available to make this messages "CAN-SPAM" compliant (i.e. add unsubscribe links, and allow members to unsubscribe from receiving emails from individual members, groups or the entire site. I have searched, but I cannot find.