SPF "-all" attempts to say semantically that "email not from a certain
IP is forgery" where from a senders perspective "any email I send is
not a forgery".
No it does not say it is a forgery, it says that the sending MTA is
not authorised (by the domain owner) to send mail on behalf of that
domain.
http://spf.pobox.com
"SPF fights email address forgery..."
One thing I have learned today (well it is tomorrow already) is that
SPF appeals to sys admins,
Which is not surprising as SPF is a system admin tool.
So thus as I said, you will not get same reaction from the perhaps million
novice personal domain ownsers.
You re-inforce my opinion that getting SPF "-all" supported by those novices
can not keep up with the rate that new domains are registered.
Thanks,
Shelby