We got a huge trackback spam DDoS the last days that caused our servers to be unavailable for some hours. Most probably caused by some botnet. That's really a pain, you're so defenseless against that kind of threat. Filtering them is like trying to stop ants from entering your house by closing their entrance holes.
But anyway, I decided to write some abuse-mails to the contacts of some of the source IPs. I even got ONE reply (from Neighbourhood Cable, if you're looking for an ISP in australia, have a look at them, they must be good). I also got this:

<k55k559@bora.net|/webmail/mbox5/bora.net/961/k55k559|2|204800|209715200|99999999|99999999|>:
Recipient's maiilbox is full, message returned to sender, (#5.2.2) [7mallot:(209715200), usage:(209874944) [0m

<saehym@bora.net|/webmail/mbox0/bora.net/865/saehym|2|51200|58454016|99999999|99999999|>:
Recipient's maiilbox is full, message returned to sender, (#5.2.2) [7mallot:(52428800), usage:(58474496) [0m

Now, who in the world gives IPs out to people who aren't able to configure their mailboxes? Boranet, the source of that, seems to belong to the company LG, also producing Hardware. Maybe an interesting fact when you buy your next CD burner.