iExpense - Links in Workflow emails for external access

Hello,

We are in the process of opening our EBS to external access (DMZ configuration), outside our firewall. Our need is to have users create and approve expense reports outside of our network.

Are there any profile options/other settings necessary for iExpense, apart from making the responsibility available for external node? For example, for iSupplier I can set external URL profile option. I am concerned about the email links in workflow emails that go out for approval action. The embedded links are pointing to the our internal URL thus will not work outside the firewall. How can I fix this?