What is a PST file? A PST file (personal storage file) is Microsoft Outlooks file format for email storage. This single file, is a compound file, like a ZIP file, and can contain thousands of emails, contacts, tasks, and calendar entries.
To view the contents of a PST file, the file can be mounted in Outlook or specialist forensic tools such as EnCase or FTK can be used.
PST files are important, if not critical, in forensic and electronic discovery investigations as they provide one of the primary storage methods for email within companies.
As email is the primary form of communicaiton not investigating PST files, is akin to missing out most of the evidence in a case (assuming the PST files exist in the first place).
Prior to Outlook 2003 the maximum size of a PST file was 2 GB, however this limit has now been removed.