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Re: Email peering

  • From: Mike Leber
  • Date: Fri Jun 17 19:09:47 2005

On Fri, 17 Jun 2005 [email protected] wrote:
> > Similar concept, same scaling problems; it just hides the explicit 
> routing
> > from the user (as would any modern "peering" system, presumably).
> Then you are presuming wrongly. Nowhere in what I wrote have
> I suggested any changes in the existing email technology. I am
> not suggesting that we drop SMTP in favour of your favourite
> old dusty protocol. I am suggesting that we need a system of
> accountability for people who run Internet email servers based
> on contracts and SLAs, i.e. peering agreements.

In between the choice of accepting mail from *anybody* by default which we
have now and the choice of accepting mail from *nobody* by default that
explicit peering agreements represents there is another solution; which is
to accept mail only from IPs that have *some relation* to the sender's
>From domain, for example by MX record or by reverse DNS (we implemented
that test and call it MX+).

Here is a downloadable reference implementation for use with procmail:

The example program mxplus is code that was carved out of the mail server
software we use and made standalone.  It's an antispam option that works
well for many users.  The example includes sender email address
validation, which is another test like MX+ that works well for most users
and breaks under usually acceptable circumstances when senders do bad
things like send email with an invalid From address.  YMMV.


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