Exchange 5.5 2 Orgs in 2 domains issues

Have the following setup:

Domain1-
192.168.228.0 network
one exchange 5.5 server
smtp mail = username@domain1.com
dns server

Domain2-
192.168.230.0
one exchange 5.5 server
smtp mail = username@domain2.com
dns server

Exchange server in domain1 previously contained smtp addresses from domain2 before being split off. All reciepents have been removed that had domain2 in their address.
Servers can resolve exchange server on other domain, but all mail fails (host unreachable).

There is no connectors or trusts between the domain or exchange.

Any suggestions?

Thanks.