Microsoft pwns SPFv1 and calls it SenderID.
A tip on the Spamtools list said to bear in mind that it's mostly spammers and bulkers who publish such records. Therefore, rejecting mail based on the existence of the records might indeed be useful.
You should only reject on SPF if the rule says so. Yes alot of spammers have set up SPF records.. but SPF is not designed for Stopping Spam. Xtra have only set "v=spf1 ip4:210.86.15.0/24 ?all" instead of "v=spf1 ip4:210.86.15.0/24 -all" The existing record will make the result neutral (tested for SPF but still allowed to come in) instead of fail for people testing for it. If they set "v=spf1 ip4:210.86.15.0/24 -all" then some mail (for example that trademe.co.nz sends out) would get rejected as it would be coming from the wrong place Thanks Craig