May I ask what TCO was calculated before implementing the described architecture and what amount really arouse regarding TCO? Regards, Robert Kehl We have exactly the same configuration and OWA has been published on our DMZ. Our DMZ is only between a ZYWALL box with ADSL VPN installed and our ISA. Outside we have different offices with again ZYWALL boxes and VPN connected to the main site. OWA is working fine and OUTLOOK the same. For mobile users we open from their destops VPN session on our ISA directly and TSE sessions giving them on our TSE boxes all what they need and OUTLOOK the same Seems also that we don?t need more..GD