Short description of Outlook Express Security 2.31: Use Outlook Express Security to control access to Outlook Express and its databases. When it is active, Outlook Express becomes locked and no third-party programs can access its message base files and the address book. As a result, when you try to start Outlook Express, open the address book or access the files, a password will be asked to allow access. If an invalid password is entered, Outlook Express or Address Book will not be opened.