[Asrg] Round 2 of the DNSBL BCP - "collateral damage"

[Seth]

Rich Kulawiec <rsk at gsp.org> wrote:

> I'm well aware of SPF (and DKIM, and SenderID).  Whatever their
> theoretical merits, I don't consider them worthy of serious
> operational consideration, as spammers/phishers already have the
> ability to render them moot whenever it pleases them to do so.

For domains I trust (including all banks I do business with), I use
SPF to allow stuff they send me to bypass spam filters.  That enables
those filters to be much stronger for stuff that looks like bank
messages.

How would you suggest a spammer can render that moot?

Seth