Hijacked email address.

[Ugo Bellavance]

kent at songbird.com a écrit :
> On Thu, Apr 17, 2008 at 01:31:49PM -0400, Ugo Bellavance wrote:
>>> There is NO way to prevent people from forging your name to the From: line
>>> on an e-mail message.
>> False.  
> 
> No, it's true.  There is no way to prevent people from forging the From: 
> header. 

Ok.

> 
>> SPF can help.  DomainKeys can help.
> 
> These things help detect forgeries after the fact, but they don't do
> anything to prevent forgeries in the From: line.  They aren't designed for 
> that purpose.  

Exact, but if the recipients are rejecting messages based on a SPF 
hardfail, for example, the result will be that there would be no 
backscanner (which is what the OP wanted to prevent).

>>  Some other mechanisms like 
>> watermarking in MailScanner, and there is also something called EMEW in 
>> BarricadeMX (http://www.fsl.com/barricademx.html).  There might be other 
>> means, I only know those.
>>
>> For SPF and DomainKeys, it depends on the proportion of mail servers 
>> that check them.
>>
>> For the 2 others, it assumes that all of your outgoing mail is going 
>> through the MailScanner/BarricadeMX system(s)
> 
> A forged email can come from any server in the world.

What I meant is that with watermarking, any e-mail that comes from the 
empty enveloppe, is validated with a watermarking, that allows the 
incoming server to determine if the original e-mail that caused the DSN 
was originating from itself.  If it doesn't it can simply reject it, 
still achieving the goal of the OP.

Ugo