If you require the conversion of data from OST to PST Outlook format, so I suggest you the best solution of KDETools for OST to PST converter utility. The software can smoothly work to export and migrate emails, contacts, calendars, tasks, attachments, public folders, etc. from an offline OST and online Exchange server.
Updated features of KDETools OST to PST Converter
Transfer bulk OST to PST Outlook via the ‘Batch Option’.
Fully support all editions of MS Outlook and Windows OS.
No file-size limitations of offline OST files and the users can migrate any file size.
Convert offline OST to PST Outlook without installing Outlook on your system.
OST to PST converter