@fsniper We generally notice core mail server problems fairly fast (we did this time too), but in general I feel humans are very bad at noticing when a regular thing stops happening. To fix this we'd have to build some additional sort of alert notification other than email, and we don't really have that available.
(In theory we could SMS or something, but the budget for SMS alerting is $0 and I don't think there are any free gateways.)