On Fri, 2010-11-12 at 08:50 +0200, Jeremy Van Rooyen wrote: > This snippet is what I get in my email log(quit allot of them > everyday). On the user side I get the following (bounce back email): > > "Delivery Status Notification (Failure)" or "Message Undeliverable!" > with the original email attached which is spam. > ... generally known as 'backscatter', its the result of a spammer randomly generating recipient names at example.com and forging your address as the sender. If you set up an SPF record for your domain this will cease to be a problem because an SPF-aware spam target will discover that the sender is forged and not bother to send a delivery failure notification. AFAIK this use of SPF is typically an MTA function at SMTP time and does not require SA to be SPF-aware.
Backscatter has became quite rare here once I set up an SPF record. I'm not aware of any adverse effects caused by it either. Use the wizard at http://www.openspf.org/ to generate a correct SPF record and, after installation, validate it with the test tools at http://www.kitterman.com/spf/validate.html Martin
