FIX: When a .NET Framework 2.0-based application sends e-mail messages by using the System.Net.Mail namespace, the FQDN is not sent when you send a HELO or EHLO command


In the Microsoft .NET Framework 2.0, you have an application that sends e-mail messages to a Simple Mail Transfer Protocol (SMTP) server by using the System.Net.Mail namespace. When you send a HELO or EHLO command to the server, only the local computer name of the client is sent to the server. However, you expect the Fully Qualified Domain Name (FQDN) of the client to be sent to the server.


Hotfix information

A supported hotfix is now available from Microsoft. However, it is intended to correct only the problem that this article describes. Apply it only to systems that are experiencing this specific problem.

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

You have to modify a configuration file to enable this hotfix. For more information about how to do this, see the "More information" section.


You must have the .NET Framework 2.0 Service Pack 1 (SP1) installed to apply this hotfix.

Restart requirement

You do not have to restart the computer after you apply this hotfix.

Hotfix replacement information

This hotfix does not replace a previously released hotfix.

File information

The English version of this hotfix has the file attributes (or later file attributes) 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 item in Control Panel.
x86 versions of Microsoft Windows 2000, Windows XP, or Windows Server 2003
File nameFile versionFile sizeDateTimePlatform
System.dll2.0.50727.18542,985,98403-Sep- 200803:07x86
x64 versions of Windows 2000, Windows XP, or Windows Server 2003
File nameFile versionFile sizeDateTimePlatform
System.dll2.0.50727.18542,985,98403-Sep- 200802:44x86
System.dll2.0.50727.18542,985,98403-Sep- 200803:07x86


Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.

More Information

After you install the hotfix, a new option named clientDomain is added to the configuration file, and a property named ClientDomain is added to the SmtpNetworkElement class. This hotfix lets you change the domain value by using a configuration file.

Note If you do not modify the configuration file to enable the clientDomain option, the local computer name will be sent by default.

The following is an example of how you can use the clientDomain option.
<smtp deliveryMethod="network">
Note You must replace FQDN with the value that you want System.Net.Mail to use in the HELO and EHLO commands. Typically, this is the FQDN of the host.


Section of RFC 2821 specifies that an SMTP client should use FQDN as part of its HELO or EHLO message to a server. For more information, visit the following Internet Engineering Task Force (IETF) Web site: For more information about software update terminology, 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

ID do Artigo: 957497 - Última Revisão: 08/10/2011 - Revisão: 1