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Q161118: XCLN: Troubleshooting POP3 Connections to Exchange Server

Article: Q161118
Product(s): Microsoft Exchange
Version(s): winnt:5.0
Operating System(s): 
Keyword(s): kbtool
Last Modified: 06-AUG-2002

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The information in this article applies to:

- Microsoft Exchange Server, version 5.0 
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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 versions
  4.0 and 5.0 do not support IMAP4. For IMAP4 support you must upgrade to
  Microsoft Exchange Server version 5.5. 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:

  Q153119 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 Microsoft Outlook with
  the Internet Mail information service in the client profile or use Microsoft
  Outlook Express.

7. Verify that the Private information store database is consistent and not
  corrupt. This can cause POP3 login's to fail and POP3 sessions to hang after
  a command has been issued.


If the problem still occurs, contact the manufacturer of the e-mail client for
additional assistance.

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

  Q161116 XCLN: POP3 Supported Command Set for Exchange Server 5.0

  Q155048 XCLN: Troubleshooting Startup of Windows Client Using TCP/IP

  Q153119 XFOR: Telnet to Port 25 of IMC to Test IMC Communication

Additional query words: ims imc

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Keywords          : kbtool 
Technology        : kbExchangeSearch kbExchange500 kbZNotKeyword2
Version           : winnt:5.0
Issue type        : kbhowto

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