After the replacement of my personal PC, I needed to recover for personal use the old UST file converting it to PST. Among a lot of softwares, I have found DEXR.EXE that fitted exactly my purpose. Whilst the UI looks very simple, DEXR was able to recover all my emails, contacts and contact groups with no errors. I well keep in mind DATANUMEN for the future as a reference Brand for data recovery.