If you’ve ever tried to delete or rename a PST file directly after opening it in Outlook 2007 then you were probably shocked to find that you couldn’t do so…or at least not for a while. This is because Outlook maintains a lock on a PST file for thirty minutes after it’s been closed. This can be quite bothersome, especially while troubleshooting an Outlook profile issue or migrating and verifying mailboxes and archived mail.
We can fix this by creating a registry entry to modify this behavior. To do so, open regedit and browse to HKCU\Software\Microsoft\Office\\Outlook\PST. Once here, create a new DWORD entry named PSTDisconnectDelay. This entry will allow you to modify how long the PST lockout duration is, in seconds. Keep in mind that this value is read when Outlook is started, so you will have to restart Outlook if it is open when you make this change.