I need to create a duplicate of my entire mailbox, folders, sub folders

Dear @Lara Portelli,

I hope you’re having a good day 

Based on your description, it sounds like your goal is to preserve a complete copy of your mailbox, including folders and subfolders, before your organization's email purge takes place.

From what I've been able to find, the closest Microsoft-supported capability to what you're describing has historically been the ability to export mailbox data to an Outlook for Mac archive (.olm) file. Microsoft documents this process in: Export items to an archive file in legacy Outlook for Mac

However, it is also important to note that Microsoft has announced the end of support for Legacy Outlook for Mac, so this should be viewed as a transitional option rather than a long-term strategy if Legacy Outlook is still available in your environment.

Reference: End of support for legacy Outlook for Mac

Microsoft documentation and previous Microsoft responses indicate that OLM import/export functionality is associated with Legacy Outlook, which aligns with your observation that this workflow was available in the previous Outlook experience.

For a longer-term approach, you may also want to check whether your organization provides an Online Archive mailbox. Online Archive is designed for long-term retention of email within Microsoft 365 and allows older messages to remain accessible and searchable without requiring a separate local mailbox copy.

Reference: Exchange Online Archiving service description

If your primary requirement is an independent backup that you control, then exporting to an OLM archive from Legacy Outlook would likely be the closest match to what you're looking for.

If your goal is simply to retain access to historical email within the Microsoft 365 ecosystem, then an Online Archive solution may be the more sustainable option.

I hope this information helps clarify the options currently documented and supported by Microsoft.

Thank you, and I wish you all the best.

Warm regards,  

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