The best program for recovering OST file data and converting OST files is SysInspire OST to PST Converter. This program can also open and view OST files. OST can be converted to PST, EML, EMLX, Yahoo, Gmail, Zimbra, HTML, MSG, vCard, and more formats. From damaged or corrupted OST files, it also restores all addresses, conversations, attachments, contacts, notes, papers, and a range of other information. SysInspire also provides a free trial version.