Can the system forward a message from the user inbox to my private e-mail?

The system cannot forward a message from the user inbox to your private e-mail, but it can send a notification of a received message in the user inbox. You can activate the delivery of notifications to your private e-mail in the user inbox under the Settings option.

With which digital credentials can I use all electronic services?

The highest security level credentials, such as an electronic ID card (eOI) allow access to all services. In order to use an eOI, it is necessary to have a smart card reader. You can find other high security level credentials on the list of accepted credentials.