QUOTE(Miss Betsy @ Sep 8 2006, 10:26 AM)

If the volume is up, that can mean a compromised machine that does not use the normal port 25 to send the spew. Check your firewall logs for unusual traffic.
and the PSBL evidence shows real fresh spam rather than bounces, which also suggests either a trojanned machine or an SMPT-AUTH hack, rather than the problem being simply auto-replies.
There is also now one human report to add to the spamtrap hits:
Submitted: 08 September 2006 08:11:27 +0100:
Fwd:
* 1912415028 ( 210.9.130.146 ) To: abuse[at]connect.com.au
(which will have reset the delist clock)
looks like the reports are going to your upstream, you might discuss with them getting copies of the reports or registering your own abuse address. It seems you have a real 'live' problem to deal with here, things seem to be going from bad to worse.