... take one of the returned spams that has all 
the header info. and forward it to your system's 
administrator that takes care of spamming and 
other account abuse.  Eventually, this will go to 
whomever is in charge of documenting the actual 
spammers.  While there are at present no 
effective laws against doing things like this, as 
soon as there are, these people will be out of 
business very quickly.

It's my understanding that most spam is 
orchestrated by no more than a hundred spammers, 
many of whom are now known by name and address to 
spam-hunters.

(No, Dragonfly isn't one of them.)