Database linked with Outlook

Our team is saving mails inside folders created in Outlook (see screenshot). The available / supported amount of space is reached, access is now very slow. Outlook also doesn't provide a comfortable handling of folders. What I need is the following: - a database to save our folders and mails - database must be linked to Outlook, so all can be done without having to siwtch to Outlook - access for all team members - solution must be professional/easy to overlook and understand kind regards Thomas