Outlook for Mac (Legacy) question

Question

Running MacOS Monterey 12.7.6, and Outlook 16.89, the latest version that runs on my Mac.

I'm kind of old-fashioned. I like having all my emails stored locally and I back up religiously. I have tens of thousands of emails organized into hundreds of folders, sitting in a massive folder tree under "On My Computer". I keep my Inbox almost empty and file what I want to keep into category and subject folders so I can find them easily.

The email account linked to "On My Computer" will soon be going away. My question is, if I delete this account from my Accounts list, is Outlook going to delete these hundreds of folders and tens of thousands of messages, or would they stay and still be accessible?

Answer 1

Hi Dan Ehrmann, 

I hope you are doing well ! I just want to check if you have had a chance to test the steps earlier? Please let me know if they helped resolve the issue or if you are still experiencing any difficulties. I am here to assist you further.

Best Regards

Answer 2

Dear Dan Ehrmann, 

Thank you for reaching out to the Microsoft Q&A forum. I understand you are using Legacy Outlook for Mac on macOS Monterey and you have a large folder tree under “On My Computer”. Your email account will soon be retired, and you want to know whether removing that account from Outlook will also remove the locally stored folders and messages, or whether they will remain accessible. I am happy to assist you.  

To answer you question: Items stored under “On My Computer” are saved only on your Mac and are not synchronized with a mail server. Because they are local-only, removing the server account does not remove the data stored in “On My Computer”; you should still be able to access those folders and messages in Outlook on that Mac.

To protect your “On My Computer” folder tree before removing the account, please:  

• Export your local mail to an Outlook for Mac archive file (.olm): In Legacy Outlook for Mac, go to Tools > Export, select the items you want to export, choose Continue, pick a save location, then Save and Finish. This creates an .olm archive you can store anywhere for safekeeping (including another drive). Keep that .olm file as your guaranteed backup.  
• See: Export items to an archive file in Outlook for Mac - Microsoft Support 
• There has been an end-of-support timing for Legacy Outlook for Mac, including that it will stop working against Exchange Online mailboxes starting October 2026. If your retiring account is an Exchange Online mailbox, plan a transition path accordingly. See: End of support for legacy Outlook for Mac - Microsoft Support 

Thank you for your understanding, please let me know when you have further updates. I am here to help.

Look forward to hearing from you.

Answer 3

Deleting the email account from the Accounts list will not delete the folders and messages stored under On My Computer.

Items in On My Computer are stored only on the Mac, not on the mail server, and are accessible through Outlook regardless of the server account status. Removing the associated account stops server synchronization for that account, but the local On My Computer folders and their contents remain and continue to be accessible in Outlook, as long as On My Computer folders are shown in the sidebar.

If On My Computer disappears after changes, it can be re‑enabled via:

1. Outlook > Preferences > General
2. Under Sidebar, clear Hide On My Computer folders

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References:

• About On My Computer folders in Outlook for Mac
• Import email messages, contacts, and other items into Outlook for Mac