Exchange 2010 Transport Rule is being applied to internal mail.

Exchange 2010

I set up a transport role that redirects any email that contains a specific user (RestrictedAddress) in the To: or Cc: line to a moderator address.

I don't want any emails copying RestrictedAddress to go outside our organization.

But when I enable the rule, it gets applied even when the email is only addressed to internal users.

Here's what I want:

a) mail from internal users to internal users (including the user named RestrictedAddress) to flow normally.

b) mail from internal users to external users (as long as RestrictedAddress is not on the to: or cc: line) to flow normally

c) mail from internal users to external users copying RestrictedAddress to get redirected to a moderator

#a) is what is failing.  These emails are also getting redirected to the moderator.

I thought that Transport Rules only apply to mail leaving the organization.  This rule is clearly applying to all mail, even mails not directed to any outside users.

Any ideas?

Thanks.