Scanpst.exe is a utility program to fix corrupted PST file, it came when you installing Microsoft outlook as part of Microsoft office program.
What is PST file?
PST file is personal file contains email that part of Microsoft outlook program. As PST file can hold all emails and folder, the file size can be huge. When 1 file become too large, it becoming prone to corrupt.
Windows 7 Pro 64 bit – Outlook 2016: C:\Program Files (x86)\Microsoft Office\root\Office16
Scanpst.exe location on Microsoft office 2013
C:\Program Files\Microsoft Office\Office15
Scanpst.exe location on Microsoft Office 2010
C:\Program Files\Microsoft Office\Office14
Scanpst.exe location on Microsoft Office 2007
C:\Program Files\Microsoft Office\Office12
How to run Scanpst.exe to fix PST file:
To run scanpst utility you need to close outlook first. Run the scanpst.exe and browse the PST file you want to repair. When Scanpst found error, it will repair the error and make backup of original file.
The repair process could take hours depend on how big is your PST file. I recommend you to repair it when you finish work and let the computer on if file size more than 10GB. You can check the result next day in the morning.