Re: Fighting Spam with <User Unknown> messages.

Ian Andrew Bell (
Mon, 01 Mar 1999 11:47:47 -0800

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Note: This is also a useful function for Mothers-in-Law,
Ex-Girlfriends, Tim Byars, and the jocks from your old high school who
are looking for you to get them jobs @ Cisco.


Ian Andrew Bell wrote:
> Typically, those guys who sell SPAM lists are now promising to
> "guarantee" that all email addresses that they have harvested are real,
> operational email addresses. To me, this implies that they are sending
> out test SPAMs and waiting either for you to try to unsubscribe yourself
> (which oddly never seems to work) or for no reply at all -- indicating
> that it's reached an active recipient.
> BUT, if they do receive a reply from SMTP that claims a "User Unknown"
> error I'll bet they delete that address from their data set
> lickety-split.
> SO, what's needed is a convenient way for our hero, the End User, to
> generate fake "User Unknown" messages to bounce back to SPAMmers
> conveniently.
> Unfortunately, to make it look legit you'd have to change your name &
> email in your preferred client which is way too inconvenient. And you
> wanna do it fast before the SPAMmer's email address gets invalidated by
> their ISP.
> One way to do this could be a web page. Specify a mailhost and your
> email address on a form, along with the spammer's address. Have the CGI
> open an SMTP connection directly to the spammer's mail server and spoof
> a reply from the mailhost you specified. Insert a generic User Unknown
> message quoting your email address and Bob's your uncle!
> I'd do this, but it requires some creative SMTP/TCP spoofery that I
> don't fully understand. Also I haven't written actual code in years,
> and HTML bores me.
> Anyone wanna discuss this? Let's get some VC and build a startup around
> this! Maybe @Home will buy us out! (joke)
> -Ian.
> .:|:..:|:.

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