You can instantly use 100% free ost to pst converter tool to convert bulk OST to PST Outlook with all attachments. Its quickly split large size of PST files. The most trustworthy way to convert ost to pst free online is to helps of the its application which has many features for migrating email, email and so on from OST to Outlook PST simply. The migration tool supports all Windows and MS Outlook editions.
More info- Import OST to PST