Hi @Meghan Clack ,
Welcome to our forum.
According to your description, I understand that your emails were stored in an original .ost file and you would like to re-access them in a new environment with imap or pop account, is it right?
If so, please first understand that OST files could only be opened/accessed via the email account used to create it in a given profile, and recreating the same email account does not "re-use" an existing OST file, which means we couldn't access the original .ost file directly with a new profile in outlook.
For your requirement, I have tried to researched some workarounds about it and found many users recommend us to convert the .ost file to .pst file via some tools, so that we could open/access .pst file in Outlook.
It's suggested to search for some convert tools for your need, and for your reference, here are some tools that I found about converting an .ost to .pst: Convert an Offline File (.ost) to a Personal File (.pst)(Please Note: Since the web site is not hosted by Microsoft, the link may change without notice. Microsoft does not guarantee the accuracy of this information.)
Hope that would be helpful to you.
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