joe-jobbed, block 'undeliverable' messages?

[Chris Yuzik]

Hi Guys and Gals,

One of our domains has been joe-jobbed, big time. We're seeing multiple 
"undelilverable" messages per minute, and in some cases many from the 
same IP. This is the worst I've ever seen it. Short of sitting here 
adding each IP to a block list, is there any way I can filter these 
things out, tag them as spam, anything?

Thanks,
Chris