GainTools OST to MSG Converter is an efficient software designed to convert large OST files into MSG format smoothly and safely. It allows users to export selected OST files to MSG and easily change their Microsoft Outlook file format while saving the converted data locally at a preferred location. It also provides a preview option to review the selected OST file before conversion. The application supports Windows 11, 10, 8.1, 8, 7 and other Windows versions in both 32-bit and 64-bit environments. It supports MS Outlook versions including 2003, 2007, 2010, 2013, 2016 and 2019.