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Comment by arcza | Hacker News Reader

how does on prem Exchange ActiveSync send notifications to iOS?

I would have never guessed the answer. Looks like the answer is the classic "it depends" which I expected but the most likely answer is

What is Microsoft 365 or Office 365 Push Notification Service?

From

https://learn.microsoft.com/en-us/exchange/configuring-push-...

How do I enable push notifications?

In order to enable push notifications, the on-premises Exchange 2013 servers must connect to the Microsoft 365 or Office 365 Push Notification Service to send push notifications to iPhones and iPads. Exchange 2013 on-premises servers route their update notifications through the Microsoft 365 or Office 365 notification services to remove the need for enrolling developer accounts with third-party push notification services.

So it goes like

1. Your server 2. Microsoft server 3. Apple server 4. Device

So this begs the next question: does Microsoft require warrants to disclose these notifications?

i know it might sound like something from an alien movie but my setup is 100% on premise with no Azure or O365. I did some googling which says an "HTTP PING" is kept going like a long running socket essentially. I think I'd still need to pcap the Exchange cluster to determine what happens before and after a notification fires.

I'm not sure if long running sockets are allowed on mobile phones these days. They were pretty normal for a couple of years, but phone battery life has increased substantially since Apple and Google started streamlining the notification system and basically sleeping background services that would otherwise poll for notifications through sockets. You'll still get your notifications, but (hours) late.

You may instead want to pcap a mobile client to see where the notification is coming from, I bet the server still phones home somehow. It's possible Apple exempted themselves from their notification policies and integrated their Exchange push services into the OS power manager like they did their APN service, but I'm not sure if I'd expect them to put in that much work for what's essentially a competitor.

As a side note, because it's not made clear during setup: the Outlook app for mobile phones will keep a copy of your email on Microsoft's servers (and a partial copy on the device); if you use that app, Microsoft will poll for updates the normal way and likely still push the notifications through Apple's servers, despite you not having set up any direct connection from your server to the cloud. This isn't the case for the built-in email clients, of course, but the Outlook app seems to be quite popular for Exchange accounts.

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