Ayush Tech Software's OST converter can convert OST files in formats like MSG,HTML,vCal,vCard,MBOX etc. File. It Split oversize of PST File into Small PST up to 5 GB Supported This tool supports all the versions of MS Exchange Server and this tool also supports on MS Outlook version up to 2019 (32 and 64 Bit). ATS OST Converter supports on Window version up to Window 10. Try the free demo version of the convert and get a magnificent chance to recover the 30 emails for free.