[AusNOG] Disturbing new spam trend?

[Ross Wheeler]

On Thu, 8 Oct 2015, Noel Butler wrote:

> On 07/10/2015 13:41, Ross Wheeler wrote:
>> On Wed, 7 Oct 2015, Chris Prangnell wrote:
>> 
>>> Your friends mailserver needs TLS enabled. Then it would have not accepted
>>> the mail.
>> 
>> He got the backscatter... the "undeliverable" message.
>> How would either TLS or SPF have helped in this instance?
>> 
>
>
> SPF if setup correctly using hardfail would (should) have 550'd during 
> initial connection from badguy, should not have been any backscatter 
> generated.

I'm not sure I agree.
Where mail has been accepted by (say) hotmail but then found to be 
undeliverable and bounces.... how does my friends mail server reject the 
bounce message?

Especially, given he doesn't run his own mail server, so "his mail server" 
in this instance is his ISP...?

I'm not convinced ISPs can really run hardfail based entirely on SPF 
without causing unacceptable collateral damage.