Microsoft KB Archive/872950

= Exchange users cannot connect to a Windows Server 2003-based computer when the number of concurrent incoming SMTP connections reaches 2,000 =

Article ID: 872950

Article Last Modified on 10/26/2006

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APPLIES TO


 * Microsoft Windows Server 2003, Enterprise Edition (32-bit x86)
 * Microsoft Windows Server 2003, Standard Edition (32-bit x86)
 * Microsoft Exchange Server 2003 Enterprise Edition
 * Microsoft Exchange Server 2003 Standard Edition
 * Microsoft Exchange 2000 Server Standard Edition

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SYMPTOMS
When the number of concurrent incoming Simple Mail Transfer Protocol (SMTP) connections reaches 2,000 on a Microsoft Windows Server 2003-based computer that is running Microsoft Exchange, your Exchange users may not be able to connect to the computer. The users may receive the following error message:

Error on telnet port 25:

421-Microsoft ESMTP MAIL Service, Version: 5.0.2195.6713 ready at Service not available, closing transmission channel

Connection to host lost.



Hotfix information
A supported hotfix is now available from Microsoft, but it is only intended to correct the problem that is described in this article. Only apply it to systems that are experiencing this specific problem. This hotfix may receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next Windows Server 2003 service pack that contains this hotfix.

To resolve this problem immediately, contact Microsoft Product Support Services to obtain the hotfix. For a complete list of Microsoft Product Support Services phone numbers and information about support costs, visit the following Microsoft Web site:

http://support.microsoft.com/default.aspx?scid=fh;[LN;CNTACTMS]

Note In special cases, charges that are ordinarily incurred for support calls may be canceled if a Microsoft Support Professional determines that a specific update will resolve your problem. The usual support costs will apply to additional support questions and issues that do not qualify for the specific update in question.

Prerequisites
You must be running Exchange on a Microsoft Windows Server 2003-based computer.

Restart requirement
You must restart your computer after you apply this hotfix.

Hotfix replacement information
This hotfix does not replace any other hotfixes.

File information
The English version of this hotfix has the file attributes (or later) that are listed in the following table. The dates and times for these files are listed in coordinated universal time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time tool in Control Panel.

Date        Time   Version            Size    File name      Platform --- 21-Jul-2004 18:55  6.0.3790.196      460,288  Smtpsvc.dll    x86 21-Jul-2004 18:55  6.0.3790.196    1,182,208  Smtpsvc.dll    IA-64



STATUS
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the &quot;Applies to&quot; section.



MORE INFORMATION
For additional information about how to resolve this problem if you are running Exchange on a Microsoft Windows 2000 Server-based computer, click the following article number to view the article in the Microsoft Knowledge Base:

829920 Users cannot connect to your SMTP server when the number of concurrent connections reaches 2,000

For additional information, click the following article number to view the article in the Microsoft Knowledge Base:

824684 Description of the standard terminology that is used to describe Microsoft software updates

Additional query words: XADM

Keywords: kbqfe kbhotfixserver kberrmsg kbbug kbfix kbwinserv2003presp1fix KB872950

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