From: Covington, Chris (no email)
Date: Mon Aug 08 2005 - 10:51:57 EDT
> But when I looked at my mail stats the next day, I noticed something
> interesting: During this test, the number of rejections by
> RBLs and other anti-UCE measures dropped dramatically from
> the norm, without any noticeable interruption from the
> legitimate servers I used in my test. I thought it might be a
> fluke, so I decided to test it again, setting my first
> priority MX to another public IP that has nothing listening
> on port 25, and the secondary MX pointed to my regular mail server.
I think it's an interesting idea but to work as effectively as
greylisting you would also need a non-responding tertiary MX because a
lot of ratware likes to deliver to the backup MXes to avoid the commonly
lower UCE restrictions compared to the primary. Or maybe the ratware
only delivers to the 2nd MX, not the lowest priority one, etc. It would
be interesting to see the statistics. I also think NXDOMAIN would cause
mail from your domain to be rejected by zealous MXes.
Chris
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