ISP port blocking practice

Randy Bush randy at
Tue Sep 7 01:30:04 UTC 2010

> The theory behind closing open relays, blocking port 25, etc., seems to
> be:
> (a) That will make it harder on spammers, and that will reduce spam --
> some of the spammers will find other other ways to inject spam, but
> some will just stop, OR
> (b) Eventually, we'll find technical solutions to *all* the ways spam
> is injected, and then there will be no more spam.
> There's little evidence for either.

the empirical evicence seems to support this theory.  spam has
continually increased, wich occasional dips when the spammers have to
find a new path when an old one is covered.

i suspect that, if we opened smtp relays again, unblocked 25 for
consumer chokeband, etc., total spam received would likely increase a
bit.  but my guess, and i mean guess, is that the limiting parameter
could well be how many bots the perps can get, not how well those bots
are blocked.

but, let's look at the upside.  with the dying economy, the spam war
provides employment for many of our friends.


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