XCLN: Troubleshooting POP3 Connections to Internet Mail Server

Last reviewed: February 3, 1998
Article ID: Q161118
The information in this article applies to:
  • Microsoft Exchange Server, version 5.0

SUMMARY

This article lists steps to help you troubleshoot problems when you attempt to connect to the Internet Mail Server from an e-mail client using post office protocol version 3 (POP3). These steps are based on information in the Request for Comments (RFC) 1725 and RFC 1939 specifications.

MORE INFORMATION

Basic Troubleshooting

If you are unable to connect to the Internet Mail Server from an e-mail client using POP3, use the following steps to troubleshoot the problem. After performing each step, check to see if the issue has been resolved.

  1. Verify that the e-mail client is POP3-compliant. Many e-mail clients are not POP3-compliant. In particular, many newer e-mail clients support Internet Mail Access Protocol version 4 (IMAP4). Microsoft Exchange Server does not support IMAP4. Microsoft Exchange Server supports POP3 as defined in the RFC 1725, RFC 1734, RFC 1939, and RFC 1953 specifications.

  2. Use the Telnet tool to connect to the Microsoft Exchange Server. To do so, follow these steps:

    a. On the e-mail client, start Telnet. For the host name, type the

          name of the Microsoft Exchange Server computer, and for the port 
          type, type 110. If a "term type" is requested, do not type 
          anything. For example, type the following command to start Telnet:
    

             telnet <server> 110
    
          where <server> is the name of the Microsoft Exchange Server 
          computer. If you are running Windows 95, Windows NT Workstation, or 
          Windows NT Server, you can type the above command at a command 
          prompt or in the Run dialog box. If you are running Windows NT 
          Workstation or Windows NT Server version 3.51, you can open the Run 
          dialog box from the File menu or the task list.
    
          When you type the above command and then press ENTER, a message 
          similar to the following should be displayed:
    
             +OK Microsoft Exchange POP3 server version 5.0.1457.10 ready
    
          NOTE: The version number might be different, but it should be 
          5.0.1457.10 or later.
    
       b. Enable local echo for the current Telnet session. To do so, on the 
          Terminal menu, click Preferences, click the Local Echo check box to 
          select it, and then click OK.
    
       c. Type the following command, and then press ENTER: 
     
             user <domain>\<username>\<mailbox>
    
          where <domain> is the name of the domain in which the user's 
          account is located, <username> is the user name, and <mailbox> is 
          the user's mailbox. Note that the <mailbox> portion of the above 
          command is only necessary if it is different from the <username> 
          portion. When you press ENTER, "+OK" (without quotation marks) 
          should be displayed.
    
       d. Type the following command, and then press ENTER:
    
             pass <password>
    
          where <password> is the user's password. When you press ENTER, the 
          following message should be displayed:
    
             +OK User successfully logged on
    
       e. To determine if the user has new messages, type "stat" (without 
          quotation marks), and then press ENTER. After you press ENTER, the 
          following message should be displayed:
    
             +OK <x> <yyyy>
    
          where <x> is the number of new messages and <yyyy> is the total 
          size of the messages in bytes. This is known as a "drop listing."
    
       f. To end the Telnet session, type "quit" (without quotation marks), 
          and then press ENTER. When you press ENTER, a message similar to 
          the following should be displayed:
    
             +OK Microsoft Exchange POP3 server version 5.0.1457.10 
             signing off
    
    
NOTE: The above POP3 commands can only be used to troubleshoot problems when you attempt to receive messages. A POP3 client uses Simple Mail Transfer Protocol (SMTP) to send messages. For information about how troubleshoot problems when you attempt to send messages, please see the following article in the Microsoft Knowledge Base:

   ARTICLE-ID: Q153119
   TITLE     : XFOR: Telnet to Port 25 of IMC to Test IMC Communication

Additional Troubleshooting

If the problem still occurs, perform these steps. After performing each step, check to see if the issue has been resolved.

  1. Verify that the POP3 protocol is enabled for the site Protocols container and the Protocols container on the server.

  2. Verify that POP3 support is not disabled for the user's mailbox.

  3. Verify that the client can ping the server using the server's Internet protocol (IP) address and the server's computer name.

  4. Run the Rpings.exe tool that is located on the Microsoft Exchange Server CD-ROM. Rpings.exe runs on the server; a client program must also be run on the client. If you are running Windows or Windows for Workgroups version 3.x, run Rpingc16.exe on the client. If you are running Windows 95, Windows NT Server, or Windows NT Workstation, run Rpingc32.exe on the client.

    NOTE: The Rpings.exe tool is used to determine if the client can connect to the server using remote procedure call (RPC). POP3 clients do not connect to the Microsoft Exchange Server computer using RPC.

  5. Try to use the Microsoft Exchange Windows NT client to connect to the server from the same computer on which Microsoft Exchange Server is installed.

  6. Try using a different e-mail client. For example, use the Microsoft Exchange client and the Internet Mail information service included with Microsoft Plus! or use Microsoft Internet Mail and News. The Internet Mail information service is included with Windows NT Server and Windows NT Workstation 4.0. For information about how to obtain Internet Mail and News, please see the following article in the Microsoft Knowledge Base:

          ARTICLE-ID: Q154457
    
          TITLE     : Availability of Microsoft Internet Mail and News
    
    
If the problem still occurs, contact the manufacturer of the e-mail client for additional assistance.

MORE INFORMATION

For additional information, please see the following articles in the Microsoft Knowledge Base:

   ARTICLE-ID: Q161116
   TITLE     : XCLN: POP3 Supported Command Set for Exchange Server 5.0

   ARTICLE-ID: Q155048
   TITLE     : XCLN: Troubleshooting Startup of Windows Client Using 
               TCP/IP

   ARTICLE-ID: Q153119
   TITLE     : XFOR: Telnet to Port 25 of IMC to Test IMC Communication


Additional query words: kbfaq ims imc
Keywords : XCLN kbtool
Version : 5.0
Platform : WINDOWS
Issue type : kbtshoot


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Last reviewed: February 3, 1998
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