8. But the bigger problem for "-all" in SPF, is how will an ISP ever know
that all of it's users are sending all their email over the approved IPs?
It is simply impossible for an ISP to ever know that. An ISPs user can
access the internet with a different ISP, and then set their From: address
to the first ISPs domain. I do that all the time when I travel.
If I were running an ISP, I'd tell people, "don't do that." In fact,
this is exactly the position I take at work. How can we claim any kind
of accountability for mail if we don't control the servers it originates
from? IMHO this only prohibits something that was a bad practice to
begin with.
Thought you were going to let me signoff and get some sleep :)
That is very naive.
Well good thing you are not the CEO of a major consumer ISP such as AOL or
Earthlink. You would quickly stand down from that stance when you lose 5% of
your customers in short time. Money talks, bravado walks...
Fact is that people think their email is THEIR email address, not yours (as the
sys admin). You just try to tell them where they can type their email address
in From: lines and you will learn very quickly who is the owner of the email
address. :)
Thanks,
Shelby