Based on resolving missing transactions from PayPal recently and Adyen last year I have an unverified impression that the Gr4vy IPNs are a little less reliable than the ones direct from the Gateway. Obviously we need to get all IPNs.... so we need to work around this shortcoming. I fairly significant number seem to be missing - I *think* there have been times they have not sent them
I *think* we are getting IPNs for gravy transactions both from Gravy and direct from the processor and ignoring the direct ones. However, I also suspect it would be fairly trivial to stop ignoring the Gravy ones when they come from the processor and instead 'process whatever we get when we get it'' - we do this with the reconciliation files and it has cleared out all the missing Gravy ones & it feels like it might be a small reliability win with relatively little work (obviously for those gateways were we already have IPN handling code)