I doubt that anyone can stop this. There are various bodies you could report them to; spamcop. knujon, abusix, your ISP, the sender's ISP. If the messages are spoofing a legitimate business, then that business may have an address or webform for you to report spoofing, phishing and malware-laden email messages. (Ironically, while many of these bodies welcome reports about spam, some of them will refuse an infected message.) Some or all of these agencies might get the offending source IP address onto a blacklist. But if the sending is being done by an "owned" computer, i.e. a machine that has been compromised by malware, unbeknown to its user, then you may succeed in getting it closed down. The best outcome would be for the ISP to manage the connection and help the user to get rid of the malware. But in due course the spammers will move on to using another "owned" machine, which is why I'd say no-one can guarantee to stop it completely.