Ever since I updated to 15.4 on my iPhone & iPad, the mail app stops fetching new mails in the background from my set schedule (15 minutes) after a few days, and I stop getting any notifications or even an updated badge on the app icon. And after that I have to open the app manually for it to...
the iOS Mail app is not performing the scheduled fetch for favourite mailboxes of accounts (like Gmail, Yahoo, IMAP third party) which do not support Push. Notifications for such new mails are also not generated. Scheduled fetch and notifications do not occur with any of the fetch frequencies...