Question : prevent internal Exchange Server's name from showing up on internet message header of outgoing mail

How can I prevent our internal Exchange Server's name from showing up on internet message header of our outgoing mail?  

We recently implemented a single-server Exchange 2003 organization on our network.  The Exchange Server sits behind a Fortinet firewall device with an external IP, 65.xxx.xxx.48.  Our external MX record (mail.company.com) points to 65.xxx.xxx.49 which is set up as a Virtual IP on the Fortinet that points to our Exchange Server's (mail.company.local) internal address, 192.168.1.20
Any mail sent from our internal network to an exteranl recipient goes out through the firewall.
I noticed in a test message sent to my Comcast email account from my company account that the message header contained the following line:
   Received: from mail.company.local (mail.company.com[65.xxx.xxx.49](untrusted sender))...

Is there a way to prevent the Exchange server's local network name from being avaialble to the receiving mail server?  Could showing the internal server's name be a risk to us?  It seems to me it would be something a spammer would like to know.

Answer : prevent internal Exchange Server's name from showing up on internet message header of outgoing mail

Go into Exchange System Manager, servers, your server, protocols, smtp, properties of smtp virtual server, under delivery tab, advanced button.  Set your FQDN for what you want people to see in banners etc.  This should be its real public FQDN probably should be the same as mx record or a record etc, but this is where you would set mail.company.com rather than mail.company.local.