The safest tool for splitting large PST files into several smaller ones is the MacSonik PST Splitter Tool. As a result, results are completely safe and there is no data loss. Additionally, this application is easy to use. One PST file can include multiple folders, including inbox, outbox, contacts, calendars, notes, and journals. Outlook PST files are split into folders.. Both technical and non-technical users will find splitting Outlook PST files easy with this application's simple user interface.