When we've opted to relay, we've made the choice that **we** are taking responsibility for delivery, which in most cases means sending it towards the public internet. Whomever we attempt to send the message to will be seeing **our** external IP as the SPF sender.

With that being the case, when relaying, when is it **ever** appropriate to consider the senders IP for the SPF evaluation?

Having different SPF rules for outbound is A Very Good[TM] point.