Searching on the web, I found this instructive post that seems very helpful for those users who are looking for a solution to know how to convert OST to PST. Here I am also going to share a post that will also help you to convert accessible and inaccessible OST files. From this post, one can also download a free version of KDETools OST to PST Converter tool.
I recommend to use DataVare OST to PST Converter tool to recover and convert Offline OST files into Outlook PST file format with 100% data accuracy. The tool is available with free demo edition to give complete satisfaction for all users before purchase the license version. It is a standalone application that doesn’t required any third party application to complete the process so go with this software to solve out OST to PST migration related issues.
You can try MailVita OST to PST Converter for Mac Tool this application easily to transfer Offline OST file to Outlook PST file format on Mac. The tool recover damaged OST files without any hassle. This utility easily maintains email folders to restoring CC, BCC, To, From, and attachments. The technology supports all MS Outlook and Mac OS versions like - 10.14, 10.13, 10.12, 10.11. You can download the free trial versions software.