When converting a large OST file into PST, exporting the entire mailbox is not always required. Many users only need emails from a specific period, such as project-related conversations, old business records, or important communication from a particular date range. I was searching, and I found the Aryson OST to PST Converter to be a useful tool for this purpose. It also converts OST to PST and various other file formats. https://www.arysontechnologies.com/blog/how-to-convert-ost-to-pst-with-easy-methods/