I have two ideas that I think would be great:

1) The folder automatically sees all the senders added to the folder and a new option (toggle) allows you to automatically add all of them to a rule that automatically sorts the senders into this folder (a check box could allow all current emails to be sorted in as well as all future emails) - this is automatically updated when a new sender is added to the folder. In settings, you can changed the settings for each folder > sender, for example to allow push notifications for a certain sender or to make a sender an exception to this folder rule.

2) In the folder options (which is where you can set the folder to send push notification or not when setting up the new folder), I would add a toggle that allows you to choose when the contents of the folder will be deleted, for example - contents automatically delete (or alternatively are archived) after 30, 60, 90, 180, or 365 days of sitting in the folder.

Update: I also want a feature where I can automatically add tags to specific senders...