Precisely my point stuartbe
I'm not talking about NTL applying one of the domestic anti-spam programs but instituting a process that identifies the source of spam and applies a block.
Examples would be attempts to send the same mail to a dictionary list clearly designed to test for valid addresses and other such methods used by the spammers.
I'm no tech but simple logic tells me it must be possible to identify and eliminate some of the more obvious abuses of the system and start with those.
No more nor less than that.