Re: misconception in SPF

Hi Paul,
At 11:33 07-12-2012, Paul Smith wrote:
>Do people really send messages with a return path of 
>'noreply@example'? Or, do you mean that people use a return path of 
>'noreply@<their own domain>'?

I used "example" as an example.  I misunderstood what you meant by 
reply.  I was referring to what's used as the author address.

I don't recall whether noreply@example is used in the envelope for 
delivery failures (assuming valid messages).  There are valid 
messages with an invalid Return-Path.  This may due to some 
assumptions about how email works.

>With the former, I'd expect a large number of those messages to be 
>blocked/discarded (it's common to do call back verification, or just 
>simply check that the sender domain

Call-back verification can be used to trigger a Denial of Service.

Regards,
-sm