In order to open and access your corrupt, old, orphan or inaccessible OST file simply convert OST into PST file format. You can opt Magus OST to PST converter to create PST from a OST file keeping the folder structure and other data intact. You can try out the tool before you buy it.
Conversion of MBOX file into PST file format is very common but when you have to do it manually then it is complicated. Try Magus MBOX to PST converter and import PST to MS Outlook with this reliable MBOX conversion wizard. This tool allows you to convert multiple MBOX files into PST in batch. Besides this, you can also convert MBOX into EML , MSG, PDF and HTML formats too.