Hi @Martin K,
Thanks for posting in our Q&A forum.
To create a folder structure like the one you described, you can use Exchange Web Services (EWS) to develop folders and items in Exchange. You can create different types of folders in EWS, such as email message folders, calendar folders, contact folders, and search folders. Please refer to: https://learn.microsoft.com/en-us/exchange/client-developer/exchange-web-services/folders-and-items-in-ews-in-exchange
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