Description: Unistal OST to PST Converter Software successfully convert OST file to PST file at the time when Exchange server goes down. Unistal OST to PST Converter has nothing to do with the corrupt OST files, Software just convert OST files (Healthy OST). Unistal OST to PST Converter is a Professional Exchange OST Recovery Software that supports to convert ost files with all of its items like emails, journals, calendar, notes, tasks, contacts, attachments.