You can trust the vMail OST to PST Converter Tool and execute the secured conversion from OST to PST format in few moments. This tool safely exports OST to Outlook PST along with the complete mail properties, email, and attachments in the PST file. It supports OST Files of all Outlook versions to convert single or bulk OST mailbox in a single go. You can download the free demo version and export 10 emails from each mailbox folder.
Know more info- https://www.vsoftware.org/ost-to-pst-converter.html
Convert OST to PST Manually
Open Outlook and go to the File menu.
Select the Import/Export option.
Choose Export to a file.
Select Outlook Data File (.pst)
Choose whether to export a specific folder or the whole account.
Check the Include subfolders box.
Next, select a destination for the Export, and then click Finish.
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Willjoe