I've just found a new and interesting spam source - legitimate bounce messages

[eculp at casasponti.net]

In the last hour, I've received over 200 legitimate bounce messages  
from email services as a result of someone having used or worse is  
using my email address in spam from multiple windows machines and ip  
addresses.  The end result is that I am getting the bounce messages.   
I'm sure that others on this list have experienced the problem and  
maybe have a solution that I don't have.

The messages are allowed through my obspamd/pf and pf smtp bruteforce  
blocking rules because they are completely legit.

I guess the work around is to filter them on incoming together with  
our local bounce messaages util the spammers get tired of my address.

Thanks for any suggestions,

ed