XADM: How to Configure Microsoft Exchange Server with Proxy Server

This article explains how to configure Microsoft Exchange Server to operate behind Proxy Server 2.0 to handle incoming Internet client requests (this is known as "reverse-hosting").

Simple Mail Transfer Protocol (SMTP) servers and Post Office Protocol (POP) clients on the Internet must be configured to contact the Proxy Server computer through the appropriate port in order to communicate with the Exchange Server computer.

NOTE: this article is specifically for running Exchange Server behind Proxy server. If the two products are to be installed on the same computer, this article does not apply.

In addition, versions of the Wspcfg.ini file need to be placed in the directory where the server application's .exe files are installed. Because Exchange Server has more than one .exe file, more than one Wspcfg.ini file is needed in specific directories.

1. Install Winsock proxy client from the proxy server Mspclnt share.
2. Copy two instances of the Wspcfg.ini file.
3. Add the following section to the end of the first Wspcfg.ini file. This section is required for the Exchange SMTP service:

      [Msexcimc]
      ServerBindTcpPorts=25
      Persistent=1
      KillOldSession=1
    
   					

4. Place this file in the directory where the Msexcimc.exe file is located. The default directory path is \Exchsrvr\Connect\Msexcimc\Bin.
5. Restart the Microsoft Exchange IMS Service.
6. Confirm that the SMTP port is bound to port 25 on the Proxy Server computer. Do this by typing telnet <proxy external IP> 25, where <proxy external IP> is the external IP address of the Proxy server.
7. The second Wspcfg.ini file contains entries needed for the Exchange Store (Store.exe), as follows:

   [Store]
            ServerBindTcpPorts=110,119,143
            Persistent=1
            KillOldSession=1
   						

   Additional ports can be listed in this because Store.exe sets POP mail on port 110, NNTP on port 119, and IMAP4 on port 143.
8. Place this second Wspcfg.ini file in the directory where Store.exe is located. The default directory path is \Exchsrvr\Bin.
9. Stop and restart the Exchange services, or restart the Exchange Server computer, for the new settings to take effect. You should be able to contact the Exchange Server computer by connecting to the external IP address on the Proxy Server computer using IMAP, NNTP, or POP3 protocols.
10. Verify that your DNS MX records point to the Proxy Server computer and not to the Exchange Server computer. Because the MX record is different from the regular GetHostByName call, you must configure network TCP/IP properties, using Control Panel, to use DNS for the Exchange Server computer. The WinSock Proxy client application automatically redirects the DNS MX request.
    

NOTE: If you have an internal DNS server on your network, you can use DHCP to configure the internal server. This may enable you to use both internal and external DNS servers to resolve names on your internal network and on the Internet.