On Tue May 24 2005 14:15, Valdis(_dot_)Kletnieks(_at_)vt(_dot_)edu wrote:
On Tue, 24 May 2005 19:05:22 +0200, Frank Ellermann said:
No, you don't check SPF whereever you like it. SPF defines
the border of the sender, the only point where that makes any
sense at all is your border. You can't check it behind your
border, you check it at mx23.mrf.mail.rcn.net
So it defines the border of the *sender*, and then the *receiver*
border box has to do the check? Somehow that seems mildly busticated.
Maybe it should define the receiver border as well?
Good trick. Especially if a receiving MTA sees its IP address as an
RFC 1918 address, necessarily different from the A records that would
be returned by a DNS lookup.
Another known technical omission is a specification for how the
receiver is supposed to determine the sender's borders (N.B. MX
records are of zero use, as they apply to receiving, not sending,
and many sites use separate hosts for sending and receiving (i.e.
a sending host has a different domain name and IP address from
the receiving hosts listed in MX records)).
Moot point, really, since sending can take place from any of as
many clients as there are in use collectively by users who have
mailboxes (for receipt of delivery notifications, since the
discussion is related to MAIL FROM) associated with a given domain.
Basically, reality is emailers (doctors and others) without borders.