If you want to convert OST to PST then you can try OST to PST Converter software. This software easily OST to PST and various file formats such as Zimbra, Gmail, EML, EMLX, vCard, ICS, MSG, Office 365, Live Exchange server, MBOX and etc. This software shows a free preview of OST to PST email with an attachment. This software converts OST Contacts and Calendar to PST. This software maintains folder structure and email properties during the conversion process.
More info- Export OST to PST