SANS Internet Storm Center, InfoCON: green is discussing Spam Backscatter, (Mon, Oct 9th). “Over the weekend I dealt with the rather massive after effects of a spam campaign spoofing a domain” …(more)
I'll second that! As the article goes on to indicate, many innocent mail administrators are a part of the problem by not changing naive settings of their servers. We need to encourage all the mail server software authors to change their default behaviors to fail to deliver mail silently: bounces from non-existant mail addresses are clogging the internet's pipes with replies to spoofed senders. “No such postbox” and “mailbox filled” are courteous, but since your server likely doesn't really know the sender, it's not just a waste of effort, but a an imposition on others to read your counter-spam. Let's all be a little quieter and learn more from listening than responding.