When using Microsoft Outlook without an Exchange server your data is stored in a local file on your computer. This file is called a personal folders file and the filename has the extension pst. Unfortunately pst files are subject to corruption so it’s always a good policy to have a backup, just in case. You can use the Microsoft Outlook Personal Folders Backup tool to create and maintain a backup copy of your Outlook data. Instructions for installation and configuration can be found here.
Do NOT make the mistake of putting the pst file on a network drive. Pst files were designed for local use only and when used across a network are prone to corruption. You can read more in the post
Network Stored PST files … don’t do it!
