Tool for validating sender address as spam-fighting technique?

[Marcelo Maraboli]

John L wrote:
>> I phrased it wrong.  You are not responsible for the content, but you 
>> are responsible for the mail domain and that includes verifying that 
>> mail is validly from your domain you are responsible for.
> 
> Oh, OK.  So if someone sends pump and dump with a chad at shire.net return 
> address, and I do a callback and your MTA says "yup! that's a 100% valid 
> address!" then I turn you in to the SEC, rignt?  You have now confirmed 
> that the mail is from you, after all.  Or if you haven't, what purpose 
> did the callback serve?
> 
> There is some reasonable validation technology coming along, most 
> notably DKIM which which I presume you are familiar.  But callbacks are 
> not it.
> 

I agree..... callbacks are not enough, you can reach a
false conclusion, that´s why I use SPF along with callbacks...

on the same message, my MX concludes:

"you are sending email "from chad at shire.net", but shire.net
says YOUR IP address is not allowed to send email on behalf
of that domain, therefore YOU ARE FAKE/FORGED" ..---> reject

regards,

-- 
MSc. Marcelo Maraboli Rosselott
Jefe Area de Redes y Comunicaciones  (Network & UNIX Systems Engineer)
Ingeniero Civil Electronico, CISSP  (Electronic Engineer, CISSP, MSc.)

Direccion Central de Servicios Computacionales (DCSC)
Universidad Tecnica Federico Santa Maria         phone: +56 32 2654071
Chile.    http://www.usm.cl                 http://elqui.dcsc.utfsm.cl