As any human being I receive tons of emails. And 99.9% of them can wait. But in some cases the emails might be critical, such as Cloud Console billing alerts or servers downtime alerts. I want to be notified about such emails any time as soon as possible and in the most explicit manner possible. The iOS devices have this "critical alerts" api. It bypasses all kinds of notifications blocks, bed time filters and so on and screams like an alarm until acknowledged. It looks like neither Gmail nor Apple Mail uses this feature. Are there any other third party apps that can do this?