Accessing OWA inside the firewall

Split DNS.
You need a zone on your internal network for example.com, with the zone populated with the public IP address of your public web site and the internal IP address of your Exchange server.

http://www.amset.info/netadmin/split-dns.asp

Simon.

I set up a new DNS zone "example.com" with host As for "mailmx" using both pubilic and private IPs. Now I am unable to open our public website "example.com" inside the firewall and still cannot access "mailmx.example.com"

As my instructions stated, you need to replicate what you have in your public DNS. That means if you access the external web site with www.example.com then you need to add an entry for www in that zone and enter your public IP address. If you are accessing the public web site with example.com then you need to create a new A record with a blank host and put in your external IP address.

Does the host name that you entered actually resolve? If you ping mail.example.com does it respond with the internal IP address of the Exchange server?

Simon.

Yes, the "www" host does take me to the public website now, but the "mailmx" host still times out.
Ping of "mailmx.example.com" recieve reply from public IP
New DNS forward zone
example.com
          www = public IP xxx.xxx.xxx.xxx
           mailmx = pvt IP xxx.xxx.xxx.xxx

Have you attempted to use hosts files or anything that could override the DNS entry?
Do you have more than one DNS server? Is the zone on all of them?

Simon.

I cleaned out the hosts file just "127.0.0.1" now but it made no difference.

The host still doesn't resolve correctly?

Simon.

I tried several hosts file entires, but no luck.