I would like to imagine this is more for awareness. Why would exchange server want to include x-originating-ip? Is it for validation and authentication? Do we not trust people who have obviously have authenticated as people with the privilege to send emails from a certain server?

Do we need to include this information in our email headers? Is it not enough to include the IP address of the mail server? Perhaps there is a need to do this?

I was just listening to Douglas Crockford[0] in a podcast where he talks about CR/LF and how we can't decide on whether A is correct or B is correct so we do both A and B which fits neither A's position or B's position so we pick something so neither side feels like they lost. The argument is that this middle-ground is worse than either side of the proposition.

Perhaps I am wrong. However, it is still good to know why we include this information in our emails. Is it simply a case of "we have this information, why not just include it?" or is it something to check against transaction logs? Perhaps a "distributed" way to add audit records of who logged on to the mail server? There had to be some reason why they included it, right?

[0] http://hanselminutes.com/396/bugs-considered-harmful-with-do...