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Why does an Outlook profile not work with a .ost datafile?

y zhang 20 Reputation points
2025-02-13T01:29:07.7033333+00:00

I tried to have set up two Outlook profiles on my windows 11 pc, one to open with a .pst datafile and another to open with a .ost datafile. But it gave warning message ".ost datafile is not a .pst datafile". What is the problem? Does an Outlook profile only work with a .pst datafile?

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A suite of Microsoft productivity software that supports common business tasks, including word processing, email, presentations, and data management and analysis.
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Outlook
A family of Microsoft email and calendar products.
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  1. Diane Poremsky MVP 336 Reputation points MVP
    2025-02-13T01:55:00.0866667+00:00

    Ost files are created by IMAP and Exchange accounts and can only be opened by the account and profile that created it. You can make a copy of the ost and open it in another profile (like you can use PST files).

    Either add the account to Outlook and let it resync a new ost file or use a 3rd party utility to convert the ost file to a PST file.

    Diane Poremsky - M365 Apps & Services MVP
    https://www.slipstick.com

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  2. y zhang 20 Reputation points
    2025-02-13T02:31:05.4266667+00:00

    If I create a new profile, may I link it to an existing Exchange email account (or a new email account)?

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