My wife has an iPhone 7+ running IOS 12. Plenty of hard drive space, no memory issues. Once or twice a week she discovers that mail has come in - which she can see if she goes to her macbook or our ipad but which DOES NOT SHOW UP ON HER iPHONE. Mail sent during the day seem to arrive fine. She has no DND or any other restrictions set at night. It just seems that when the phone is sleeping it does not get email and in the morning it doesn’t retrieve it. The other two devices do.
It’s obviously not the carrier or the email vendor. Neither the laptop or the pad are set to delete the mail from the server.
I had been using the iOS Mail App and gmail (7 different accounts) since my first iPhone 4s and have never had an issue receiving or sending mail. The ONLY issue I’ve encounter with gmail and the iOS mail app is when I use a VPN it complains that someone unknown is attempting to log into my account(s), but I still get and send all my mail. That is annoying but not a show stopper by any means. I’ve attempted to use the gmail app, which works (but I find the iOS Mail App interface to be vastly superior), but it limits the number of email accounts you can access but does avoid the VPN issue.
I’m sure that many people use it without incident. Many people use it without noticing the incidents. At first I thought it was just a problem with my account or settings or something. But I’ve since observed it among other family members and even on this very forum:
Do the messages show up if she manually refreshes? (While viewing the list of messages in the inbox, scroll down until the spinning spokes appear.)
I have noticed that the iOS Mail app often doesn’t refresh on its own (an iPhone 6s Plus and an iPhone 7, both on iOS 11 but I believe the problem was present with 10). This happens even when the phone is awake. I have Background App Refresh turned on for WiFi and cellular. Restrictions off. Notifications set to Badges. I get a lot of email, so it’s pretty obvious when it isn’t refreshing.
Honestly, I just assumed it was working as intended, and that background fetching of mail was just something done infrequently. I am my own IMAP provider (Dovecot), and figured that were I using Apple’s mail infrastructure that there would be some kind of push to the phone to keep it better updated.
I have noticed that at least one other app I have (Resilio Sync) doesn’t update in the background, even though it should. I haven’t pursued the issue with the Resilio folks, though background sync with Resilio is much more important to me than Mail requiring a manual refresh.
I would look at the following settings on both the devices that are working as desired and the device which isn’t. If they are different, set the problem device to be the same as the one(s) which are working properly.
Go into settings>Passwords & Accounts
All the emails defined (which the Mail App has potential access to) are listed there.
The very last line (underneath the accounts) is Fetch New Data
Choices are PUSH or Fetch. iCloud mail uses Push, All my others use Fetch. Push needs to be turned on via the slider at the top of the Fetch New Data screen, if Push is to be used.
For Fetch, again all the way at the bottom, you can choose Automatic or Manual and then if Automatic you can choose Hourly, Every 30 minutes or Every 15 Minutes.
Thats my only thought as to what may be causing this.
I’d suggest some things (though maybe the last one is the best option):
look at settings / screen time and make sure that downtime is turned off and that there are no app limits (though this shouldn’t affect mail access when the display is off…)
how about settings / battery / low power mode? If that’s on, I think that prevents background mail checking (though not when you actively try to retrieve messages)
is the account an IMAP or POP3? If POP3, there is a restriction from most servers that prevent multiple devices accessing mail at the same time (though normally mail would show an error message.) IMAP is preferred if you have a choice between the two.
if that’s not it, then I’d suggest deleting and re-creating the email account and see if that fixes it. Maybe it’s just a weird data corruption issue that deleting the account may fix.
I pickup email on my ancient (mid-2010) MBP (El Cap), iPad Retina 2 (iOS 11) as well as my iPhone 8 Plus.
I have noticed that Apple Mail under iOS 11 on iPhone 8 Plus sometimes doesn’t retrieve mail, even when manually requested (pulldown). This can happen at any time. The half dozen accounts that seemingly have no mail at these times include POP3 and IMAP types, one of which is Gmail. My fix is to quit (eject from ‘multi-tasking’ queue) and re-open. Things return to normal.
My POP3 provider allows multiple accesses, and this hasn’t been a problem until my new iPhone arrived.