Why SPF over PTR?
bortzmeyer at nic.fr
Tue Nov 30 08:43:25 UTC 2004
On Mon, Nov 29, 2004 at 12:12:27PM -0800,
Ludwig77 <gregrjones at yahoo.com> wrote
a message of 10 lines which said:
> I must not be understanding SPF correctly because I don't understand
> why it is better for preventing sender domain forgeries than doing a
> simple PTR lookup.
1) As explained by Barry Margolin, many mail servers are hosted by an
2) Even in the rare case when there is a one-to-one mapping
(universities, typically), not all machines whose PTR ends in
example.edu are authorized to send mail on the behalf of
example.edu. Universities host zombies, too.
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