Online retailer Amazon has sued 11 firms which falsely used its name to sell products as diverse as growth hormones and penis-enlargement therapies.
The lawsuits, filed in the US and Canada, are the latest crackdown against fraudulent e-mail marketing, a rapidly-growing business.
"Spoofers" pose as legitimate online major corporations by creating e-mail accounts that closely mimic major corporations.
Internet firms Yahoo and eBay, and banking giant Citibank have recently been hit by spoof e-mailers.
Amazon has made some progress in dealing with spoofers.
In one case, the New York Attorney General's office worked with Amazon to reach a settlement with Cyebye.com, owned by a
Brooklyn-based home appliance retailer.
Cyebye.com agreed to pay damages, keep records of future commercial e-mails and stop
using other companies' names in its marketing without permission.
Companies have been beefing up their response to spoof e-mails in recent months.
The Direct Marketing Association (DMA)
is offering to help federal investigators and law
enforcers in a new scheme, known as
"Operation Slam Spam", set to begin next month.