How to see email message content after importing a backup file Outlook 365 Mac

Dear @Julie,

Welcome to Microsoft Q&A Forum!

Thank you very much for taking the time to explain your situation. I truly understand how upsetting and stressful this experience must be, especially after taking the right step to back up your data before the change. I’m really sorry for the confusion and inconvenience this has caused.

I’d like to carefully explain what happened and what realistic options are available at this point. Also, please kindly take a look in the Q&A Assist AI first to see if it can help you.

First of all, please note that this is a peer‑to‑peer support forum. Microsoft Q&A moderators like myself, as well as other community members, share guidance based on personal experience and publicly available information. Due to security and privacy protocols, we do not have access to your internal environment and are unable to check or recover it directly on your behalf. Our role is to help guide the discussion and connect you with relevant and helpful resources. I truly appreciate your patience and understanding in this situation.

What happened:

• When your previous email provider deleted the Microsoft 365 tenant to release the email address, the original Exchange Online mailbox was permanently removed on Microsoft’s servers.
• Afterward, when the same email address was created again in Microsoft 365, it resulted in a completely new and empty mailbox. Unfortunately, there is no technical link between the old mailbox and the newly created one, this is expected behavior in Microsoft 365.
• When you imported the OLM backup into Legacy (Classic) Outlook for Mac, Outlook successfully restored the data locally on your Mac under On My Computer. However, Outlook for Mac may not sync imported OLM data back into a Microsoft 365 mailbox, and it also may not rebuild the message bodies into the newly created mailbox once the original mailbox no longer exists. This is why you can see message headers or previews, but the full email content does not appear as expected. Reference: About On My Computer folders in Outlook for Mac
• To be clear, this does not indicate that your backup file may not be necessarily corrupted, it is an expected behavior of how Outlook for Mac handles OLM imports in this specific mailbox‑recreation scenario.

In this case, I really want to find anything that may be helpful in this bad situation in order to help you. Therefore, here is a possible option to try (with important notes):

If you need to attempt further recovery, one possible idea is to:

• Convert the OLM file to a PST file, and
• Open or import the PST file using Outlook for Windows, which has broader support for importing data into Microsoft 365 mailboxes.

Please note the following important points:

• This conversion typically requires the use of a third‑party tool.
• Microsoft does not provide, recommend, or support any specific third‑party conversion tools.
• I’m unable to guide you on tool selection, setup, or usage.
• If you decide to pursue this option, you will need to research and proceed at your own discretion and responsibility.

Here is an example article for it: https://www.thewindowsclub.com/how-to-convert-olm-email-files-to-pst-format

Note: This information is provided as a convenience to you. This site is not controlled by Microsoft, and Microsoft cannot make any representations regarding the quality, safety, or suitability of any software or information found there. Please ensure that you fully understand the risks before using any suggestions from the above link.

I completely understand that this is not an ideal situation, and I truly wish there were a more direct or supported way to restore the messages on macOS alone. If there were an official Microsoft‑supported method to recover or reconnect the original mailbox, I would absolutely point you to it but unfortunately, that option does not exist once a tenant and mailbox are deleted.

I hope this information can give you some insights in this case.

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In Outlook for Microsoft 365 for Mac, imported data from an .olm file appears in the On My Computer section. If message lists are visible but content does not appear when opened, first confirm that the items are being accessed from the correct location and that On My Computer folders are not hidden.

Use these steps to verify and access the imported mail:

1. Confirm that On My Computer folders are visible:
   • In Outlook for Mac, go to Outlook > Preferences….
   • Select General.
   • Make sure Hide On My Computer folders is cleared.
2. Check where the imported .olm content is located:
   • In Outlook for Mac, on the Tools tab, select Import.
   • Choose Outlook for Mac archive file (.olm) and complete the import if not already done.
   • After a successful import, email messages, contacts, calendar items, tasks, and notes appear in the navigation panes (Mail, Calendar, People, Tasks, Notes) under On My Computer.
   • In the Mail view, expand On My Computer and open the folders there; the full message bodies should be available from those folders.
3. If the account is using an Online Archive, ensure the correct mailbox is being viewed:
   • In the folder pane, expand the primary mailbox and any Online Archive folder.
   • Only mail items are supported in the Online Archive in Outlook for Mac; other item types will not appear there.

If On My Computer folders are hidden, or if the imported folders under On My Computer are not being used to open the messages, the message list may be visible without accessing the actual stored items. Ensuring that the .olm is imported as described and that On My Computer is visible and expanded is required to view the full message content.

References:

• Import email messages, contacts, and other items into Outlook for Mac
• Use your online archive with Outlook for Mac