RFC2369?

[Ashton]

I seem to recall support for unsub via headers
but am not finding anything in the manual ...

Pointers?

List-Unsubscribe: <http://www.host.com/list.cgi?cmd=unsub&lst=list>,
          <mailto:[EMAIL PROTECTED]?subject=unsubscribe>

http://www.faqs.org/rfcs/rfc2369.html
The Use of URLs as Meta-Syntax for Core Mail List Commands                    
and their Transport through Message Header Fields