iPhone doesn't automatically get inbox' child folder mail I have the following folder structure on my mail account

INBOX
    folder1
    folder2
SENT
...


My iPhone (7plus - latest os) does only retrieve messages that are put into INBOX by my mail server, the mails going to folder1, folder2 aren't synced automatically and I will receive them only after I manually entered them inside the Mail app and do a manual refresh of the folder. 

I would need to automatically receive those messages too, but couldn't find an option to do so. 

Is it possible to sync folders automatically that are not INBOX?
You need to pick folders to push if you want to sync certain sub-folders for notifications. To do this, go to Settings > Email > Accounts > Fetch new data > iCloud, and choose which folders should be pushed automatically.

I'm using a free app called 'myMail' that lets me choose the sub-folder to get the notification when there is new e-mail. It's working perfectly with my Gmail, Hotmail and IMAP account that has around 10 sub-folders. You can try it too.