Using classic Outlook for Windows in business environments
Hello waelkd
Hi, I'm Karl and will be happy to help you today.
An OST file can only be opened in Outlook using the original Outlook profile and email account that created it. To be more specific, if you delete the email account fro the Outlook profile and re-add the same account, a new OST file will be created. There is no option that would allow using a previously created OST file.
The only way you will be able to access an "orphaned" OST file (one not associated with an active IMAP or Exchange account) is to use a (paid) 3rd party OST2PST conversion utility. There is simply no function to accomplish that from within Outlook (any version).