A password can be set for an Outlook Data File (.pst) to help prevent unintended intrusion by other people who share your computer, such as members of your family. When a password is used, a password prompt appears when Outlook starts or when the file is first opened within an Outlook session.
Security Note: Outlook Data File (.pst) passwords are not intended to provide security against intentional malicious attempts to access your information. For a better way to restrict access to your data, create a password-protected Windows user account for each person who uses the computer. For more information, see Windows Help and Support.
After you set a password on an Outlook Data File (.pst), it is recommended that you change the password periodically.
Click the File tab.
Click Account Settings, and then click Account Settings.
On the Data Files tab, click the Outlook Data File (.pst) for which you want to change the password, and then click Settings.
Click Change Password.
Note: The Change Password button does not appear if you are using a Microsoft Exchange Server account. Your network password is used to access your Exchange account and information.
In the Change Password dialog box, type the existing password in the Old password box.
In the New password and Verify password boxes, type the new password. The password can be up to 15 characters and is case-sensitive.
Click OK to set the password.
Learn more about password best practices
Use strong passwords that include and mix a minimum of eight uppercase and lowercase letters, numbers, and symbols such as Y6dh!et5. A longer and complex password helps improve password protection.
Important: It is critical that you remember your password. If you forget your password, Microsoft cannot retrieve it. Any password that you write down should be kept in a secure location, away from the information that it helps protect.
Note: Your computer can remember your password so that you don't have to type it in each time that you open the Outlook Data File (.pst). If your Microsoft Windows user account is password protected, and no other person has access to your Windows user account, you can select the Save this password in your password list check box after you verify your new password.