All PST files are discovered regardless of whether the PST is password protected.
If a password protected PST is discovered as associated (coupled) with an Outlook profile, the user may be prompted for the password as content processing begins, however, most users will have already entered (and cached) the password.
If a PST that was associated with an Outlook profile has been moved or copied using PST Enterprise to another location and you have requested to have the moved or copied PST reattached to the Outlook profile in the policy finalization action, the reattached PST is not password protected.
If the password protected PST is not associated (uncoupled) with an Outlook profile, the PST Enterprise client application automatically determines the password and processes the PST as normal.