SPF

[#1]

Does anyone know of any good reason why this technology appears to be slow on the uptake among dns/mailserver administrators?
I have been getting spam from spoofed yahoo accounts recently. If yahoo employed SPF like Hotmail, Gmail etc. than I would not have this issue. Currently I am only able to reject invalid SPF records but obviously not no SPF records.

[#2]

I don't think it'll ever get to a stage where you can safely reject mail from domains without SPF records.
The plusnet virtual domains don't have SPF entries.
The Madasafish ones do though and in my experience it sometimes causes more problems from a support perspective than it solves.