Hi our client has been using exchange 2007 with SP1 for a year now however he wants to take the mail access on the public interface ( internet) now . Basically his requirement is that OWA should be accessible from outside his permiter network . He will be using Cyberroam Firewall in front of the exchange Box.He is also going to use a NAT router which will translate the public IP exposed on the WAM to the internal LAN IP . I know its not the best way to go about it but thats how it will be . Now i understand i need to open SMTP port and the SSL port on the Firewall for communication to happen right ?? Is there any extra bit of config i might be missimg out.There won't be a firewall between DC and Exchange though ..If we are to use digitally signed certificate on the server kindly guide us as to how to install the certificate and on which servers do we need to install them.. A technet doc will be vastly helpful...

Port 443 and 25 are fine to publish OWA from Client Access server role and internet mail flow directly to/from your Hubtransportserver. For digitally signed 3rd party certificate, you need to create acertificaterequest, get it signed with public CA and import back in to Exchange server which holds Client Access role. Refer couple of article for process... Certificate Use in Exchange Server 2007 http://technet.microsoft.com/en-us/library/bb851505.aspx Exchange 2007 and SSL Certificates - Take 2 http://blog.sembee.co.uk/archive/2008/05/30/78.aspxAmit Tank | MVP Exchange Server | MCITP: EMA | MCSA: M | http://ExchangeShare.WordPress.com

thanks a lot