"LISTSERV list owners' forum" <[log in to unmask]> wrote on 
08/02/2005 11:06:23 AM:
 
> It seems like I'm always hearing about "blocked" addresses or ISPs.  Is
> there any such thing as adding addresses to an "approved" list instead 
of a
> "blocked" one at the list administrator's level?

Yep, they're called whitelists.  Blocked servers/domains/addresses are 
blacklists.

The questions is, "How did that address end up being blacklisted?"