Maisie User This tool is efficient enough to convert multiple MSG files into PST file format in batch. There are no file size limits of 2 GB to bulk convert MSG files to PST format. It offers the possibility to divide the resulting PST into customised file sizes. Outlook installation is not required to convert MSG files to PST. It generates a Unicode PST file to overcome limited file capacity problems and offers the possibility to automatically detect MSG files to speed up the process.