marking dynamic ranges, was fixing insecure email infrastructure

J.D. Falk jdfalk at
Tue Jan 25 17:43:06 UTC 2005

On 01/25/05, Markus Stumpf <maex-lists-nanog at Space.Net> wrote: 

> I am generalizing on what I see from about 300 mailservers and about
> 1 million messages a day.

	One million ain't much by today's standards.  That gets lost in
	the noise at any of the bigger providers.  I'd question whether
	that gives you a sufficiently wide sample.

	(I'm also surprised you need 300 servers to handle such a small
	load -- what is that, ~3333 messages per server per day?)

> As you can see, we don't filter out "no revDNS", too. But setting
> MTAMARK records would give the admins of the receiving mailservers
> a hint as how to classify the sending IP.

	Sure!  It's a great idea...but if you could get every site in
	the world to cooperate on ANY great idea, we'd be way ahead.

J.D. Falk                                          uncertainty is only a virtue
<jdfalk at>                    when you don't know the answer yet

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