[throwaway290232]

Yeah, I totally agree it's really out of left field compared to what users are comfortable with. Like another commenter said, clients would probably laugh you out of the room for proposing it. (though that's half my point! why are we only accepting these half-baked custom solutions on janky platforms? fear of criticism? is it really saving anyone any time or money compared to the "weird solution"?)

But I'm not convinced on the latency/compute/storage comparison with Kafka or other solutions. I think a POC would need to be built and perf tested, and then tweaked for higher performance and lower cost, like most software. Considering the volume of traffic that mail software is designed for, I can't see how even a large provider like Stripe would have difficulty scaling a mail system to match Kafka. It's not like mail software is written in Java or something ;-)