Internal vs External Candidate Applications

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We are creating an internal career site in TBE that will have a unique Taleo search page (job portal and application) for employees.  Has anyone determined a way to make sure internal vs external candidate apply from the correct site within TBE?  The link to the internal career site will only be available on our company intranet.  From the internal job search page, an internal candidate could send an external person a link to the internal posting using the "send to a friend" button or by sending a direct URL from Taleo.  Also, internal candidates could apply on the external