Publish Exch2003 services (pop3,smtp,imap,owa) in DMZ, its OK for me. Which ports I need to publish that the AD/Domain Controller on the privante LAN can be accessed by the exchange server from DMZ, and use it de AD as users database (rpc,kerberos, ...), i.e, the Exch server will join as member of internat AD domain. Thanks, Daniel.