I have both a web server and email server, instead of placing these two "public" servers in the DMZ, instead In the DMZ I was going to place a Reverse Proxy.
for the Web Server: Firewall accepts port 443 into the DMZ, maybe port 80 for some static content. But let's assume all 443 for the moment. Reverse proxy is setup to reverse "/Name/" and only this traffic is sent to the actual web server on another port. All other requests for /X/ where X is not /Name/ don't get to the web server, and any request other than 443 are not accepted by the Firewall.
for the Email: Firewall accepts port 25 and forwards all traffic to the Email server.
My question, I think I have the web server nicely configured, but the email server seems flaky, what additional settings at the DMZ i.e. before it reaches the mail server be implemented?