On Fri, 16 Feb 2007, in the Usenet newsgroup comp.unix.bsd.openbsd.misc, in
article <87bqjujzkw.fsf@thingy.datadok.no>, Peter N. M. Hansteen wrote:

>What you're seein is just a side effect of spammers using from
>addresses picked at random. Yours happened to be the one they picked
>that day. When you're postmaster you tend to see a few bizarre
>variations on this. The way it plays out is usually something like
>this:
>
>1) a spammer's message somehow manages to get through to a mail server
> for one of our domains
>
>2) the message is addressed to something_undeliverable@datadok.no,

and this should cause the mail server to respond with a

550 Requested action not taken: mailbox unavailable

ending that transaction right then and there.

> and my server bounces with an "unknown user" message

Point your news reader at news.admin.net-abuse.blocklisting and find out
that this is called "backscatter" and the second fastest way to get your
IP address onto blocklists behind sending spam directly. Fix your mail
server so that it knows who is a valid recipient, and do not accept any
mail for unknowns, so that you don't have to bounce it.

Old guy