From spf-discuss: “Unless all the two hundred and twenty people on this mailing list have managed to overlook some enormous shortcoming in the draft, the design is now frozen, and the spec will only change in minor details such as the format of the Received-SPF header.
This is the draft that I am editing now. It differs from 02.9.txt in that softfail is deprecated.
In my opinion SPF goes out of its way to be “to many things to to many men”. The result is about an order of magnitude increase in complexity. This combined with the, to put it mildly, controversial appropriation of the TXT DNS RR is surely not going to help ensure widespread deployment. Personally I don’t see this being accepted as the solution to the problem of forged email.