Don't forget that spammers will often fake name/details of a company purely to get innocent businesses into trouble.
See the 5th post on my spam fighting thread where "Joe Jobbing" is explained :
http://www.cableforum.co.uk/board/sh...ad.php?t=10441
Simply doing a WHOIS on a domain, without checking the email header will often lead you to the innocent party.
* I'm not saying that this is the case for the above situation, just that it's worth keeping in mind when investigating spam.