Simple Mail Transport Protocol (SMTP):
Exchange 2000 Server was rebuilt from the ground up to support SMTP as a primary transport for messages. Its predecessors, Exchange 5.5 and earlier, used X.400 as the method to transmit messages by default. If you wanted to connect Exchange 5.5 to the Internet, you first have to add the SMTP protocol to your Exchange server using the Internet Mail Service wizard, which would install the Simple Mail Transport Protocol (SMTP) and create an Internet Mail Connector.
Exchange 2000, on the other hand, already has the SMTP service running. Even though an Exchange 2000 server could potentially send mail to the Internet immediately after it is installed, that doesn't mean that it can. Other factors include DNS name resolution, creation of an MX record and firewall access. And if you want finite control over how mail flows in and out of you organization, then you likely want to create an SMTP connector on one or more of your Exchange 2000 servers. For more information on creating an SMTP Connector, see KB article 265293, How to configure the SMTP connector in Exchange.
Domain Name Service (DNS):
In order to send mail to the Internet, your Exchange 2000 server must be configured to resolve MX (Mail Exchanger) records of external SMTP hosts. MX records are located on Public (a.k.a. Internet) DNS servers. In order for you to receive inbound mail, you must have an MX record for your SMTP domain registered on a Public DNS server. Many Exchange administrators simply use the DNS domains and servers owned by their employers. Other must first register a DNS domain and configure an MX record prior to connecting to the Internet. KB article 319426, How To Configure the SMTP Connector to Link to Internet Domains in Exchange. discusses how to configure your SMTP connector and DNS for inbound and outbound communications. You will also find information on how to configure your firewall(s) as well.
Do you have comments on this Ask the Expert question and response? Let us know.
Dig Deeper on Exchange Server setup and troubleshooting
Related Q&A from Richard Luckett
Some folders in a mailbox on Exchange Server 2013 are not showing up on the folder list in the OWA virtual directory but do appear in other views. Continue Reading
We have a Client Access Server and Mailbox Server on Exchange 2013 and we want to install an Edge Transport role on another machine. I joined the ... Continue Reading
How can I enable Outlook Anywhere to allow internal use for all users and external use for only some users in Exchange 2013? Continue Reading
Have a question for an expert?
Please add a title for your question
Get answers from a TechTarget expert on whatever's puzzling you.