2 Servers with HT/CAS roles NLB - mail not flowing

We have 2 new Exchange2007 servers running both the HT and CAS roles called HT1 and HT2 clustered with NLB using 1 NIC each.

I know that the HT role does not need NLB, but CAS does and as of SP1, it is supported... and we wanted to save a server (have 2 servers as apposed to 4 servers for these roles)/

Email is received fine from the Internet on each server but when sending out email, if it gets sent via HT1, it routes fine.  If its sent via HT2, it gets stuck in the Queue.  The delivery Type is SMTP Relay in Active Directory Site and the Next Hope Domain is HT1-Exchange2003Srv (where Exchange2003Srv is the current server that acts as the SMTP gateway until we complete the migration of all mailboxes from e2k3 to e2k7).  

So HT1 can route to Exchange2003Srv, but HT2 is trying to send mail to HT1 so it can then send to Exchange2003Srv because it does not have its own route to Exchange2003Srv.  And the reason why it cant is because the two HT servers cannot talk to each other (because NLB Unicast is enabled and they share a MAC address)

Do you know how to have HT2 send email directly to Exchange2003Srv?