Using hMailServer to test emails sent from application

I have a Java webapp that sends out email notifications to client-users in a bunch of different scenarios. The content, schedule, etc. of the mails is determined by the admin-users of the system.

I've pointed the app to a local hMailServer instance in my test environment, now I want to configure this so that all emails it receives are forwarded to a set of email addresses and blocked from being sent to the real recipients.

Since I'm setting this up so that admin-users can test out their emails before we move them into production, it would be good if I could avoid having to rewrite any of the email headers (that way the users can see that the email would have been sent to the right people).