Here is one of the best tools to convert OST to PST is MacSonik OST to PST Converter for Mac. It is the best and most professional tool to convert OST files to PST and other formats like EML, MBOX, PDF, DOC, DOCX, CSV, etc. The utility to convert bulk OST files at one time without any data loss. It has user-friendly software and does not require technical knowledge to use. Moreover, it also offers to migrate OST emails to Live Exchange, Office 365, Amazon Webmail, Yandex, Gmail, Thunderbird, etc. You can download the full-featured trial version of this software to analyze the performance. 

OST to PST Converter is a software tool that converts Outlook offline data files (OST) to personal storage files (PST). It allows users to recover corrupted or inaccessible OST files and export them to PST format. This conversion process enables users to access their emails, contacts, calendars, and other data items stored in OST files on any computer with Outlook installed. OST to PST Converter is a reliable solution for businesses and individuals who need to migrate their data from one computer to another or recover lost data due to system crashes, server failures, or other issues.

If you want to convert your OST files into PST format manually, then you can go through this informative article that provides the two best manual solutions to convert OST file to PST file format. You can choose any of them as per your choice. However, the manual methods are quite complicated to perform.

Therefore, this article will also introduce you an advanced OST to PST Converter tool which is a comprehensive solution for importing oSt files to PST file format. By using this utility, users can convert their OSt files into multiple file formats such as PST, MBOX, PDF, EML, CSV, etc. It also facilitates its users to migrate their OSt files to Office 365, Hotmail, IMAP, Gmail, Yahoo, and many other email clients. To analyze its performance, try its free demo version.

Open Outlook and go to the File menu.
Select the Import/Export option.
Choose Export to a file.
Select Outlook Data File (.pst)
Choose whether to export a specific folder or the whole account.
Check the Include subfolders box.
Next, select a destination for the Export, and then click Finish.

Regards,
Jimmy