I've searched all over Google and unable to find why these reports are named "rua" and "ruf".
They don't seem random, but also don't appear to easily translates in an obvious way to their definitions.
From the DMARC RFC:
rua: Addresses to which aggregate feedback is to be sent
ruf: Addresses to which message-specific forensic information is to be reported
Ok so I'm guessing maybe the "a" maps to "aggregate" and "f" maps to forensic. But what does the "ru" part mean?