KnowledgeBase Archive

An Archive of Early Microsoft KnowledgeBase Articles

View on GitHub

Q165312: Unable To Connect to Internet Mail over RAS with WinNT 4.0

Article: Q165312
Product(s): Microsoft Windows NT
Version(s): WinNT:4.0
Operating System(s): 
Keyword(s): kbnetwork
Last Modified: 09-AUG-2001

-------------------------------------------------------------------------------
The information in this article applies to:

- Microsoft Windows NT Workstation version 4.0 
- Microsoft Windows NT Server version 4.0 
-------------------------------------------------------------------------------

SYMPTOMS
========

After you connect your Windows NT version 4.0 Remote Access Service (RAS) client
to your Internet Service Provider (ISP), you are unable to connect to your
Internet Mail Server using your mail application. Also, you are unable to use
Telnet.exe to connect to TCP port 25 on your Internet Mail Server.

However, you are able to successfully ping your Internet Mail Server by IP
address and host name. You are also able to use mail applications to connect to
your Local Area Network (LAN) mail servers.

NOTE: This may affect Windows 95 Dial-Up Networking Clients and Windows NT 3.5x
RAS Clients as specified below.

CAUSE
=====

This issue may be caused by one or more of the following:

- This may be caused if the router at the ISP is unable to handle the 'IP
  Header compression' feature in Windows NT 4.0. (The final ACK packet on
  Windows NT 3.51 and Windows 95 is 60 bytes large; in Windows NT 4.0 it is 54
  bytes).


  -or-

- The Winsock Proxy client is installed on your Windows NT 4.0 RAS Client (this
  may apply to Windows NT 3.5x RAS client also). In this case, you are also
  unable to Telnet to local servers.

  -or-

- Your Internet Mail Server does not have an IP address assigned to the
  Multi-channel Memorandum Distribution Facility (MMDF) . In this case, the
  Windows NT Server 3.5x RAS client and Windows 95 DUN will also be unable to
  Telnet to port 25 on the Internet Mail Server.

RESOLUTION
==========

Depending on the cause of the problem, perform the following steps:

Disable IP Header Compression
-----------------------------

Disable IP Header Compression using the following steps:

1. Click Start, point to Programs, point to Accessories, and click Dial-Up
  Networking.

2. Select the appropriate entry in the Phonebook entry to dial drop-down list.

3. Click More, click Edit entry and modem properties, and then click Server.

4. Click Settings in the Network Protocols section and click to clear the Use IP
  Header Compression checkbox.

Uninstall the Winsock Proxy
---------------------------

To uninstall Winsock Proxy, use the Add/Remove Programs Control Panel tool and
remove Microsoft Proxy Client.

Have Your ISP Assign an IP Address to MMDF
------------------------------------------

Refer to the documentation that came with your Unix server.

Disable Data Compression
------------------------

Hardware compression:

1. Click Start, point to Settings, and click Control Panel.

2. Double-click the Modems icon, and then click Properties.

3. Click the Connection tab, then click Advanced.

4. Click to select the Use Error Control checkbox, then click to select the
  Compress Data check box.

Software:

1. Click Start, point to Programs, point to Accessories, and click Dial-Up
  Networking.

2. Select the appropriate entry in the Phonebook entry to dial drop-down list.

3. Click More, click Edit entry and modem properties, and click Configure.

4. Click to select the Enable Modem compression checkbox.
======================================================================
Keywords          : kbnetwork 
Technology        : kbWinNTsearch kbWinNTWsearch kbWinNTW400 kbWinNTW400search kbWinNT400search kbWinNTSsearch kbWinNTS400search kbWinNTS400
Version           : WinNT:4.0
Issue type        : kbhowto

=============================================================================

THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES SO THE FOREGOING LIMITATION MAY NOT APPLY.