[Mimedefang] Spam ethics question

- kd6lvw at yahoo.com
Thu Jan 14 17:12:21 EST 2010

Playing games with spammers is fun.  You could always do something like this:

DNS records:

fake.hostname.example.com.  IN  MX  10  tarbaby.junkemailfilter.com.
                                MX  20  mail.example.invalid.
                                MX  30  localhost.
                                MX  40  @              ;itself.
                                MX  50  mx.fakemx.net.
                                A        ;any non-routable.
                                AAAA    2001:DB8::1    ;any non-routable.
                                SPF     "v=spf1 -all"  ;never a sender.

localhost.                  IN  AAAA    ::1
                                SPF     "v=spf1 a -all"

All but the #2 MX resolve.  The first and last are trap hostnames that always reject (but log the sender). Some spammers skip the first and/or last MX entries.  The fourth generates timeout delays or "no route to host" errors.  If the spammer can resolve "localhost" (the third) and accept the mail for relay, this could catch the spam in a loop on the spammer's machine (at least until a "Received:" header loop detector catches it).  "Sit and spin" is a good result for a spammer.  Delivery only occurs with "localhost."

As for the original question, send the spammer a mailbox redirection to a mailbox under your fake hostname and let them sit and spin.  ;-)

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