spf-draft-200404.txt -- Happy spammers

The latest specification says:

> 2.2.2. Lookup
> ...
> If the domain does not exist (NXDOMAIN) an SPF client MUST return
> "unknown".
>
> 3. SPF Record Evaluation
> ...
> Unknown: indicates incomplete processing: an MTA MUST proceed as if a
> domain did not publish SPF data.
This will make the spammers and virus authors happy. Now they simply have to
use a return-path with an non-existing domain, and their spam or virus will
be delivered.

Roger