1. Ensure that you have successfully established an account with your email provider.
2. Go to 'Accounts' and select the email account you are having issues with.
3. Click 'Add' to add the account.
4. Check if a 'Mail Folders to Sync' option appears.
5. Select the 'Folders' option and check if the 'Include subfolders' is enabled.
6. Click the 'Done' option to save your changed and sync the account.