Permanently remove all deleted content from PST and OST files

Supported on: At least Windows Server 2008 R2 or Windows 7

Registry

HKCU software\policies\microsoft\office\16.0\outlook\pst

Value name: pstnullfreeonclose

Enabled: pstnullfreeonclose = 1

Disabled: pstnullfreeonclose = 0

Description

By default, a small percentage of deleted data is not overwritten in Outlook PST and OST files. By enabling this setting, all deleted data in PST and OST files is overwritten when users exit Outlook.