What is a Staging Server? When should I use the Staging Server? Can I use both Staging and Proxy architectures at the same time?   What is a Staging Server? ITA Secure Messaging, by default, uses a Proxy architecture for receiving e-mails from clients, which processes e-mails as they come in and forwards them to the actual SMTP Server. Staging Server is an alternate design and may provide certain benefits depending upon your network design. The following table discusses the differences between Proxy and Staging server. Proxy Server Staging Server Emails are delivered as they come in Emails are queued and delivered at a later time No need to provide a list of acceptable domain names. It gets this information from your corporate SMTP server. You need to provide a list of acceptable domain names. SMTP authentication is automatically handled for out bound messages. Cannot authenticate users before accepting outbound e-mails. For out-bound messages you need to configure ITA Secure Messaging as an open-relay for local IP addresses and block outside IP addresses through your firewall. ITA Secure Messaging cannot forward e-mails to multiple servers. ITA Secure Messaging can send e-mails to multiple servers based on the domain name ITA Secure Messaging cannot be used to filter out-bound e-mails if you use any protocol other than SMTP. For example, MS Exchange service. Corporate e-mail server can be configured to send out-bound message via ITA Secure Messaging. In case of MS Exchange this is done via Smart Host.   When should I use the Staging Server? There are a couple of scenarios where you would want to enable ITA Secure Messaging's Staging Server: Scenario # 1 Scenario # 2 Click here to enlarge Click here to enlarge You have multiple SMTP servers and want to use one ITA Secure Messaging to route your e-mails to these servers. Here you configure ITA Secure Messaging to use the Staging server to accept incoming e-mails. After filtering the message ITA Secure Messaging sends it to appropriate SMTP server inside your firewall. You need to configure ITA Secure Messaging with acceptable domain names and which machine should ultimately receive the message. Your clients use a protocol other than SMTP to send out-bound messages and you want ITA Secure Messaging to filter those messages as well. One such example is Microsoft Exchange where clients use MS Exchange service to send out-bound e-mails, which bypasses ITA Secure Messaging. In this scenario you assign two IP addresses to the machine where ITA Secure Messaging is running. One IP accepts incoming messages and uses the Proxy architecture. The other IP is used for out-bound messages, and uses the staging architecture. You also have an option of making the staging server listen on a port other than 25.   Can I use both Staging and Proxy architectures at the same time? Yes. As long as both servers are listening on a different port (or same port different IP) you can use both of them at the same time. Consider the following scenario. Assume that: You are using Microsoft Exchange Your clients use MS Outlook, which is configured to use Exchange Service rather than SMTP to send out-bound emails Some of your client access their e-mails via "OutLook Web Access" Step 1: An email comes from the Internet and is intercepted by ITA Secure Messaging's Proxy Server. If it is not spam, message gets forwarded to the SMTP server, which in this case is MS Exchange. Step 2: Since Outlook uses Exchange server service ITA Secure Messaging never comes into the picture for out-bound message. This problem can be solved by using a staging server. Step 3: Configure ITA Secure Messaging's staging server either on a different IP listening on port 25 or on the same IP but different port. Then configure MS Exchange to use a Smart Host and specify the IP address where ITA Secure Messaging's staging server is listening. VERY, VERY IMPORTANT: Make sure not to configure the Smart Host to send it back to the Proxy server. Your e-mail message will get stuck in an infinite loop. ITA Secure Messaging will log warning messages if it encounters this scenario. Step 4: ITA Secure Messaging accepts messages through its Staging Server and sends the message out on the Internet.