After a reboot all works fine and the iPhone is receiving e-mail in the defined period of time (30 minutes). After some time of correct functionality, the iPhone discontinues e-mail receiving. For receiving of e-mails I've to open explicitly the e-mail app. I didn't change anything in the e-mail preferences. What's wrong? Very annoying.
iPhone XS, iOS 15
Remove your email account and set it up again
Make sure that all of your emails are there or make sure that your email is saved somewhere other than your device. On your device, go to Settings > Mail, then tap Accounts. Tap the email account that you want to remove. Tap Delete Account.
If you can't receive email on your iPhone, iPad, or iPod touch ...
If you can't send an email on your iPhone, iPad or iPod touch
If you can't send an email on your iPhone, iPad or iPod touch ...
Remove your email account and set it up again
Make sure that all of your emails are there or make sure that your email is saved somewhere other than your device. On your device, go to Settings > Mail, then tap Accounts. Tap the email account that you want to remove. Tap Delete Account.
If you can't receive email on your iPhone, iPad, or iPod touch ...
If you can't send an email on your iPhone, iPad or iPod touch
If you can't send an email on your iPhone, iPad or iPod touch ...
This is only a workaround for an issue I don't understand. If I enable/disable flight mode e-mails are received again. I cannot delete and create the e-mail account for every iOS upgrade.
iOS 15.5: iPhone XS discontinues e-mail receiving after some time of correct functionality
