Chris Haynes wrote:
Let's see I've understood your scenario (and SPF-Classic) correctly:
Your traveller connects to a foreign provider's SMTP server (e.g. by using a
dial-up connection) and asks it to send a message for her. We have to assume
that the foreign provider is prepared to do this for an 'unknown' client (unwise
though that may be; your traveller could be a spammer).
That foreign-MTA accepts the message from the client, stores it and then offers
the message to the destination-MTA. The destination MTA consults the
foreign-MTA domain's SPF record (not the traveller's home-domain's record) and,
for some reason, decides there is a problem with the message.
No, the problematic situation is that the traveller is using one of the many
"global roaming" arrangements allowing one set of ISP credentials to be used
at any number of ISPs worldwide. The traveller connects up using some foreign
ISP and tries to send mail through that ISP's mail server *using the
traveller's home domain*.
This is the way that global roaming currently works, but will have to change
over to SMTP AUTH using the home domain's regular servers to be compatible
with SPF, unless the home domain does something very clever to allow the user
to use another SMTP server when travelling.
Paul.