Mail App

In addition, note that only Microsoft Exchange and iCloud email addresses support push notifications, and thus are the only accounts that can notify in near real time. Gmail will also notify using Push, but only if you have the gmail app instead of or in addition to Apple Mail. And for all notifications you need to have a cellular network connection, as Push uses the cellular control channel to notify the phone of updates.

For other mail accounts you can enable Fetch in their settings in Settings/Mail/Accounts. This will periodically get mail on a schedule you choose, but it is not real time.

LD150 wrote:

Interested: How is that situation affected by being on charge as opposed to not on charge?

Good question. Having it plugged in will enable Wi-Fi when the screen is locked. It still won’t be able to receive SS7 notifications, but I don’t know how Wi-Fi Calling affects that if it is enabled. That might be able to route the notifications through Wi-Fi calling. It would be difficult to test, however.

I can't replicate their problem with my Outlook, or other mail regarding on/off charger or full/low power mode.

My Outlook mail notifies just the same whether at home or out the house, Wifi or cellular on any power setting.

icloud mail will not notify in low power mode but plugging in the charger makes no difference.

I do find that whatever setting I have in Notifications, Mail, they are still overridden in Customise Notifications (at the bottom of mail notifications) settings for each account.

No i just let wifi take over automatically, I never touch any of those controls , apart from hotspot occasionally

Sounds like you may be on Low Power mode. Is your battery icon yellow in Control center? Turn it off in control center.

Interested: How is that situation affected by being on charge as opposed to not on charge?

When you are home to you put the phone in Airplane mode and turn on Wi-Fi only, or do you leave the cellular network connected?

As long as you are not in airplane mode notifications can still arrive over the cellular control channel, even if cellular data is off.