The use case I'm particularly interested in is when the Low Power Mode is enabled. From what I understand, that feature disables some background activity, such as Background App Refresh and Push (not sure if there's a difference between the two, but anyway), which is supposed to pause the background activity of the apps installed. My concern is whether a non-default app would follow that. This article claims that:
If I have Airmail or any other third party mail app running, that app will still push and fetch mail like normal. Unless I manually disable those features inside that particular app, I’m not reaping all the benefits of Low Power Mode.
And I can see where does that point come from, because when I enable the Low Power mode, the default Mail app does actually stop fetching e-mail, while Outlook doesn't.
completedMicrosoft Outlook responded:
You may disable Background App Refresh on your iOS setting.
iOS Settings >> Outlook >> Toggle Off Background App Refresh
The thing is, Background App Refresh is already turned off and even grayed out because, again, I'm in low power mode. But Outlook still keeps somehow reciving e-mail immediately.
So this doesn't make any sense to me. I know Outlook could have some custom code polling mail servers in a loop directly, but since the emails arrive almost immediately, that'd be like constant polling which would kill the battery even faster. So that must be some kind of push, but again, it's supposed to be off while in Low Power?
There is a chance that support representative doesn't have a clue of what's going on - I had to call Microsoft once, ended up talking to their outsourced people, and that's the impression I got. So if that's the case, that means the issue is not fixed as he claimed, but that still doesn't clarify why Outlook keeps fetching mail while in Low Power.
I've tried to research as much as I can, but if I missed something, please clarify. Thank you.