> It's the fault of the company that designed the automatic alarm. Not the hotel.

The hotel picked a monitoring solution which relies exclusively on email, or configured it like that. If anything they are absolutely both to blame but for different things. The company for designing a safety related system like this, the hotel for selecting an inadequate solution/configuration thus allowing their guests to be harmed.

> But it is accurate to say that the cause of the issue was the outage

The cause of the issue is the more immediate one - the configuration of the monitoring system. This avoids going up the causality chain to far - shitty coffee caused engineer to take down email system, and such.

Email going down is the proximate cause. A system configuration relying on a single unreliable communications route is further up the causal chain.