Is there a way to automatically subscribe to every mailfolder i have?
In modern email clients you have the possibility to choose if the client should
Most modern email client let you subscribe and unsubscribe to every single mailfolder you own or give you the possibility to show every mailfolder. This solution describes how to configure your email client to show every mailfolder (despite its subscription state).
Edit the Account Settings (e.g. right click on that Account and choose Settings)
Left click on Server Settings.
Push the Advanced Button.
Make sure the Setting Show only subscribed Folder is not set.