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Simple Mail Transfer Protocol (SMTP) is the most common mode for implementing larger email installations. SMTP installations require every destination to have its own domain name, (for example, yourcompanyname.com). Mail is sent and retrieved using the SMTP protocol. The Intel® InBusiness™ eMail Station becomes the mail host or mail server responsible for managing all email services, both locally and over the Internet.
While using SMTP, all users' email accounts are defined on the eMail Station, not at the ISP. The small business owner eliminates the need to contact the ISP to add, delete, or edit user accounts.
Messages between local users are stored on the eMail Station server without being transmitted to the ISP; Messages to and from users on the Internet are forwarded through the ISP, using SMTP for both sending and receiving. This means that the eMail Station employs a full SMTP routing engine to forward email to its correct destination.
Internet mail and Domain Name Service (DNS)
When using SMTP to send and receive email you must obtain a registered domain name. Contact your Internet service provider to help you if you are not familiar with the domain registration process. Each domain name is associated with a mail server and an IP address, where mail can be forwarded and queued. This route or record is commonly referred to as a Mail Exchange (MX) record. This record is needed to route the mail from one server to the next until it reaches it destination. Your eMail Station acts as the primary SMTP mail server and is recognized by the ISP by a host name. For example, mail.yourcompanyname.com
In the example above, "mail" represents the eMail Station host name and "yourcompanyname.com" is the domain name.
The traditional method of sending SMTP mail was to forward mail from one server to the next until the destination was reached. This meant that all of the mail servers using SMTP to send and receive mail had to maintain a constant dedicated connection. Otherwise, they ran the risk of not receiving all of their incoming mail. This is due to the queuing process that SMTP uses. The mail is not really stored on a server, (such as a Post Office Protocol (POP3) server but is queued until it is retrieved.
SMTP and ETRN technology
The industry now offers ETRN technology which is a slightly different version of the traditional SMTP mail transfer process. We call it dial-up SMTP mode.
The dial-up process alleviates the need for a dedicated connection to the ISP.
To receive incoming mail the eMail Station signals the ISP that the link is up and that it can send messages across. To do this it uses a protocol referred to as ETRN to alert the ISP server. It then sends the ETRN command causing the ISP to initiate a transaction with the dial-up server. Queued messages for the server's domain are then sent.
Since the "ETRN" protocol is an optional command within the SMTP specification it may not be supported by all ISPs. If this command fails (for example, it is not supported by the ISP), you receive an error message. Alternatively, the eMail Station can use any IP gateway present on the LAN to forward mail. In this setup, the router may be connected to the ISP on a dedicated link. This eliminates the need for the ETRN command or any other type of dial-up work around. However, if the router were a dial-up type device such as the Intel® InBusiness™ Internet Station, the ETRN command is still required.
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