How to use Telnet to test an Internet Mail Connection

This article describes how to use the Telnet terminal program to test a connection to a POP3 server. The following topics are covered:

• Establishing a Telnet session to the POP server
• Using POP commands in a Telnet session

Some Internet Service Providers (ISP) may have implemented security features that may prevent Telnet access to servers within their domain.

Establishing a Telnet Session to the POP Server

Telnet is a terminal emulation program supplied with Microsoft Windows. With Telnet, you can establish a host session to a server using one of several emulation types.

To establish a Telnet session, follow these steps:

1. Use your Dial-up Networking connection to connect to the Internet through your ISP.
2. Click the Start button, point to Programs, and then click Command Prompt.
3. In the MS-DOS window, type the following:

   telnet <POP server name or IP address> 110
   							

4. Press the ENTER key. The Telnet window appears and displays a welcome message. This message will be preceded by +OK and will vary depending on the software installed on the POP Server.

NOTE: The default port defined for communications to a POP server is 110. Your ISP may have defined a different port for your server. If there is difficulty establishing a connection through the default port, consult the ISP for information about the server configuration.

Additionally, you may need to enable Local Echo to see characters as they are typed. To set local echo in a Telnet session, follow these steps:

Microsoft Windows 95, Microsoft Windows 98, Microsoft Windows Millennium Edition (Me), or Microsoft Windows NT 4.0

1. On the Terminal menu, click Preferences.
2. In Terminal Preferences, click to select the Local Echo check box.

Microsoft Windows 2000 and Microsoft Windows XP

1. Click Start, click Run, and then type telnet.exe to start the telnet program. For example, type telnet pop.microsoft.com 110
2. Type Ctrl+] .
3. Type the following command: For Windows 2000:
   
   set local_echo
   
   For Windows XP:
   
   set localecho
4. Press Enter on a blank line.

If, when you type, each letter that you type appears twice, use the above procedure to deactivate Local Echo.

Using POP Commands in a Telnet Session

This section outlines some basic POP commands that you can use to verify the connection and condition of your mail box on the POP server. Before beginning sending commands with Telnet, you may want to define a log file to capture the text of the session. To capture a Telnet log, follow these steps on a Microsoft Windows 95, Microsoft Windows 98, Microsoft Windows Millennium Edition (Me), or Microsoft Windows NT 4.0-based computer:

1. On the Terminal menu, click Start Logging.
2. In Open Log File, type a file name for the current log. Note the folder location of the file. The default location is the Windows folder.
3. Click OK.

Telnet will capture the current session as you enter commands. The log will close when you quit Telnet. You may cancel the log at any time during a Telnet session by clicking Stop Logging on the Terminal menu.

NOTE: Telnet does not have a full-featured text editor. If you make a mistake and then backspace to correct the mistake, the command may not be recognized. In most cases you will receive a command error. Reentering the command is necessary in these cases. If you make a mistake when entering the password, however, most servers will terminate the session, and you must establish a new session.

Telnet Commands

• USER

This command identifies you as a registered account on the server. After you see the server welcome message mentioned above, type USER <account name> After entering the USER information, the server will return a line that reads, "+OK Password required for <account name>."

• PASS

Type PASS <your password> If the password is accepted, the server will return a line similar to: "+OK <account name> has <n> message(s) (MMMMM) octets", where <n> is the number of messages stored in your mailbox on the server and (MMMMM) is the total size of all messages.

• LIST

Type LIST at the prompt. The server will return "+OK <n> messages <MMMMM> octets), a list of the messages including their numbers, and the individual message sizes.

• RETR

This command will retrieve the text of a message. For example, if you wish to retrieve message number 4, type at the prompt, "RETR 4."

• DELE

This command allows you to delete a message from the POP server. To delete a message enter DELE <n>, where <n> is the message number determined from the LIST command. For example, to delete message number 4, enter the command "DELE 4."

IMPORTANT: The DELE command should be used with care and in extreme cases where a specific message is blocking mail delivery. It is strongly recommended that you retrieve the text of the message into a log file as described above before attempting to delete it.

How to enable Telnet on Windows Vista-based computers and on Windows 7-based computers

1. Click the Start
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   button, click Control Panel, click Programs, and then click Turn Windows features on or off.
2. In the Windows Features dialog box, select the Telnet Client check box.
3. Click OK. A configuration window should appear. The installation might take several minutes. When the installation is complete, the configuration window will close without prompting that setup is complete.
4. To open Telnet, click the Start
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   button, type Telnet in the Start Search box, and then press ENTER.
5. To use Telnet to connect to a remote server, type open <server name> <port#> at the command prompt, and press ENTER.
6. When you are finished with Telnet, you can uninstall it from the user’s computer. To do this, return to the Turn Windows features on or off window, click to clear the Telnet Client check box, and then click OK. A configuration window should appear. When it closes, Telnet has been uninstalled.
7. To verify that Telnet has been uninstalled, click the Start
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   button, and then type Telnet in the Start Search dialog box. The search results should display a "No items match your search" message.

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For more information on configuring a Dial-up Networking connection to the Internet in Windows 95, click the following article number to view the article in the Microsoft Knowledge Base: For more information on configuring a Dial-up Networking connection to the Internet in Windows NT, click the following article number to view the article in the Microsoft Knowledge Base: