Spam Control Considered Harmful

Jay R. Ashworth jra at
Thu Oct 30 02:36:02 UTC 1997

On Wed, Oct 29, 1997 at 06:14:38PM -0600, John A. Tamplin wrote:
> On Wed, 29 Oct 1997, Dalvenjah FoxFire wrote:
> > Is there a good reason why the throwway folks (those mentioned above)
> > haven't blocked port 25 from their dialups to the outside internet?
> We are an ISP and we don't block our dialups from going to port 25 elsewhere
> because this would eliminate their ability to rightfully use another mail
> server.  This frequently occurs when a user accesses a mail server at work
> from their home dialup account.  If other ISPs did this, we would have a
> problem where a user dialing into their ISP couldn't reach their virtual
> mail server, hosted on our network.  We currently don't have many going
> the other way, but that may change.

This is roughly akin, though, isn't it, John, to the cache pollution
problems that make it pretty much a requirement to run 2 separate
nameservers: one for recursion and caching, and the other to be

Run a separate relay server, with some authentication, for users
connecting from outside your AS.

> > The only reason I can think of that would stop this would be if a
> > user subscribes to earthlink, but uses a UUnet dialin, that customer's
> > software would be set up to use the Earthlink SMTP servers.
> In our case, this doesn't help since we and all the other local ISPs block
> relay access, so you have to use the mail server of the ISP you are
> currently connected to.

Hold it.  Didn't you just say the opposite above?

I think I'm confused.

-- jra
Jay R. Ashworth                                                jra at
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