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 (every 15 minutes, every 30 minutes, hourly, Automatic) on favourite mailboxes even after a lapse of many hours/ multiple consecutive fetch cycles.
The scheduled fetch and notifications occurs for Favourite mailboxes only if its mail account supports Push, or it is manually opened.
The scheduled fetch and notifications occurs for Favourite mailboxes only if its mail account supports Push, or it is manually opened.