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Internet Email with Exchange 5.5 SMTP Connectors

 Once you are at home with your email server then it is time to organise the sending and receiving of email. SMTP is not a very complicated idea. It is, after all, the Simple Mail Transfer Protocol and runs on TCP port number 25. The first thing to do then, if you have already installed Exchange 2000/3 is to open TCP port 25 on your firewall to the internal IP of your email server and register a domain name MX record to your external IP Address. When you purchase your domain name you use a registrar to register it for you with Nominet, Verisign or whoever and I would recommend you find yourself one with ongoing free DNS management. Companies like offer email redirection but if you want to change your hosting company then they will charge your for DNS management. is the domain registration company for Pipex and I have always found them to be a fine and reliable supplier. It is your MX record (which is like a CNAME record - it points to an A record, so make sure you have already added an A record of MX0 or mail or whatever for your MX record to point to) that must be pointed toward you email server IP although it can share the connection with the web server or even be the web server as OWA is supplied with both Exchange 2000/3 versions. I recommend adding a page to the web root of your exchange server instead of manually having to type http://domain.suffix/exchange. If you are using Exchange 5.5 then you must add the Internet Mail Connector to receive mail and enable both inbound and outbound mail direction. You should also go into the routing restrictions panel and make sure only authenticated users can relay via your SMTP server as described in point 4 below:

1. Buy your domain name and edit your DNS settings so that your MX record points to an A record that is your Email Server's external IP address. For this system to work your email server MUST have a static IP address and you can find out what the address is by browsing to If you browse to and the address is changing then you will have to organise a dynamic IP forwarder which is discussed under Dynamic IP Email but which is possible with the correct software or hardware.

2. Configure your router to forward all TCP port 25 traffic to the internal IP of your email server. To test try the command "telnet [mx-recordname].domainname.suffix 25" from an external internet source to see if the connection is working

3. Create the Internet Mail Connector in Exchange Administrator from the [FILE] => [New Other] => [Internet Mail Service] and follow the instructions, your DNS server, if you have one, should be configured with an MX address for your Email Server's internal IP, otherwise the DNS settings you have made along with your domain name purchase on your ISPs servers pointing to your mail server's external IP will be sufficient. Your Exchange server must be able to connect to the Internet so make sure you can browse and that the server is using the correct DNS server according to your ISP. You will enter your SMTP domain into the connector so that it may route incoming mail to your information store and also go to the routing restriction tab on the routing tab pictured below.


4. Make sure there is a tick in the top box 'Hosts and clients that successfully authenticate' so as to prevent unsolicited spam mail being relayed through your SMTP server.

Email traffic is now moving in and out of your email server via SMTP which is the most independent email server configuration as all traffic is received and sourced by your own server. The only external services which must be maintained relates to the domain name and MX record which point to your email server. It is imperative that you have antivirus services on your SMTP gateway if you are to use this configuration as there has been no previous checks carried out upon the email arriving except on those whose systems scan the mail upon sending.

Exchange 5.5 (in its Small Business Server 4.5 form) also supports POP3 mail connectors which are created in the same way as the Internet Mail Connector and require you to have the necessary server information from your ISP or mail service providers. This will include server IP, username and password and connection type but it is no more complicated to configure than a POP3 mail client such as Outlook Express.



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Last modified: 27-Dec-2015.