bounce (171) barracuda (114) dnsbl (33) reject (14) backscatter (4) bounce spam (2) reject spam (2) backscatter spam (2) barracuda spam firewall (2)
Backscatter bounces are Non-Delivery Notifications , but they're for email you didn't send. A spammer sends out some of his spew with one or more of your addresses as the From, and poorly configured servers don't properly reject it, instead they send an NDN to the forged From address. So you get notices for something you had nothing to do with. To give you an idea of the size of the problem, I received over 10,300 backscatter bounces in the 8 months starting with October 2006. Of the bounces that specified
First, Barracuda has released a firmware update that sets the Send Bounce option to No, overriding existing settings. Better late than never. And it's not all good news, see this note for details.
Second, there have been some changes to the RFCs, and a couple of the items deal specifically with spam filtering and bounces. RFCs 2821 and 2822 have been obsoleted by RFCs 5321 and 5322. The key change from the point of view of this web site is that rejection ("bounce") messages SHOULD NOT be sent unless the receiving site is confident that those messages will be usefully delivered . Bounces for spam, viruses and a few other unwanted messages will NOT be usefully delivered since they won't go back to the