I have just been informed by Bigpipe support that they cannot set PTR records. That seems like quite a significant omission, so hopefully it's just not something support routinely handles.
I originally specified a PTR when I set up my static IP, and was not informed at the time that this wasn't offered. I assumed my request was overlooked at the time, as it was submitted early and there were a few delays with the static offering. Every other ISP I've used has allowed me to set this, even on a residential connection.
The lack of a PTR is causing problems for mail delivery, which would mostly be overcome by simply having any PTR at all, even a generic one. A small number of servers insist on the HELO matching the PTR, but that's an RFC violation anyway.
During the delay implementing statics, and since, most mail was configured to be sent via a VPS in the US. This was originally done so I could cancel my old connection, but causes another set of problems due to IP blacklists and spammers using VPS hosts. My NZ IP is clean according the RBLs I checked.