If you are concerned about battery usage, you may want to limit how often your i Phone checks for new email.
By default, your i Phone Mail app is set to "Push," which means it connects to download new email as soon as any arrives on the server.
This will reset your mobile data connection, and hopefully you'll get a better signal.
Many users have experienced various issues with i Phone, and one of them is when emails are not being pushed. User complained about Emails Not Being Pushed: If you choose Manual, you will have to launch the email client, in order to see new emails. Background App Refresh feature will refresh the app in the background whenever your i Phone is connected to Wi Fi or Cellular Data. You can perform these steps if email push now working on your i Phone, but the notifications are not appearing on the screen.
To make sure that your account settings are correct, compare the settings in the Mail app to the settings for your email account: If you have a POP3 email account, then you can only check email on one device at a time.
Close other email programs and sign out of webmail sites that you have open.
There are many issues that can cause your i Phone not to be able to download email, probably dozens.
Luckily, there are eight major steps you can take to resolve the majority of email problems.