OST to PST converter software provided by Data Recovery Freeware is the perfect tool to convert Outlook OST data files. It helps users, who are looking for an easy method to convert their OST data files with ease. It can also export password-encrypted OST files to PST format with ease. Also, The Software Swiftly exports all email messages, contacts, calendars, etc. from OST file format to Outlook PST. In the latest release, a lot of changes happened for making the product the best.
Source: http://www.datarecoveryfreeware.org/ost-pst-converter/