Re: using received headers to determine sending mta

 "Dan Field" asked:


> What are the problems with using a message headers "Received" lines to
determine the sending MTA and then perform a SPF lookup on that?
> Thanks,
>
> Dan

I can think of three reasons:

1)  There is no standard format for Received,

2)  Can you trust whoever purported to add that header to the message?

3)  If inspected long after reception, there can be problems with lack of
knowledge of subsequent changes in the SPF record in the DNS

Doubtless others will think of further reasons.

Chris Haynes