The application is defaulted to start in inbox but regardless of the setting it always starts in All Mail.

You can set the start folder with the following steps.

- Nine settings > General > Advanced > Start Nine / Folder

If it is already set as inbox, we assume that you are using Nine-badge widget to open Nine.

Please remove the widget and add a new widget.

You can set the folder when creating a widget.

Please set the folder with inbox and you can go into inbox directly.

If you are using the combined notification, you go into the All mail folder from notification because the emails are able to be come to the multiple folders. If you want to go to the received folder directly, please enable the following settings.

- Nine Settings > Your Account > Notifications > Notify for each folder - Enable