You should be aware that a vast amount of legitimate mail is sent by third party services, and in most of those cases the P1 and P2 domains will not match.
Technically, the P1 information is supposed to be the identity of the user account which generated the message. At some websites, if it knows you by your email address, and you use it to generate an email, it may send with your email address as P1. I have given up on SPF.
Doug, please vote for and comment on: In Anti-Spam, Expression-check everything after DATA or include From
Cheers - Bob
UTM is a wrapper for the Exim MTA www.exim.org
Exim has a specialized filter language which has its own manual (which I have not studied)
So the core product must have the ability, even though the UTM interface does not. I suggest one of you raise a support case to try to induce them to help you configure your filter rule directly in Exim.
Then let us know the results...
In V7.5, the Expression check allowed looking at the "To:" field, and we used that to quarantine emails sent to ex-employees. Sometime in V8, that capability disappeared. I don't recall if we used that ability to filter for spoofing in the "From:" field.
Cheers - Bob