> >>>Another case might be where you have agreed to be on a list as
> >>>a condition of receiving some service.
>
> In which case unsubscribing frees the provider from having to
> render the service. It does not allow the provider to resub the
> poor soul who is dealing with a flooded mailbox.
>
> SRE
 
The list subscribers may be generated from another data base, so
someone might unsubscribe and then be automatically subscribed
again when the list is regenerated.  I agree that someone attempting
to unsubscribe from such a list ought to be told what they need to
do to get off the list.