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FIX: Error message when you try to send e-mail by using the System.Net.Mail.SmtpClient class in a Visual Studio 2005-based application

This article has been archived. It is offered "as is" and will no longer be updated.
Consider the following scenario. In a Microsoft Visual Studio 2005 based application, you try to send e-mail by using the System.Net.Mail.SmtpClient class. You use the DeliveryMethod.Network method from the Microsoft .NET Framework 2.0. In this scenario, you may receive the following System.Net.Mail.SmtpException error message:
Command not implemented. The server response was: Command not Supported.
This problem occurs because the remote SMTP server does not support the SMTP extended Hello (EHLO) command. The exception occurs when the remote SMTP server returns the 502 reply code and the System.Net.Mail.SmtpClient class expects the 500 reply code.

Hotfix information

A supported hotfix is available from Microsoft. However, this hotfix is intended to correct only the problem that is described in this article. Apply this hotfix only to systems that are experiencing this specific problem. This hotfix might receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next software update that contains this hotfix.

To download this hotfix from the MSDN Code Gallery, visit the following Microsoft Web site:

Note The MSDN Code Gallery displays the languages for which the hotfix is available. If you do not see your language listed, it is because the Code Gallery resource page is not available for that language.

Note If additional issues occur or if any troubleshooting is required, you might have to create a separate service request. The usual support costs will apply to additional support questions and issues that do not qualify for this specific hotfix. For a complete list of Microsoft Customer Service and Support telephone numbers or to create a separate service request, visit the following Microsoft Web site:


You must have the .NET Framework 2.0 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 any other hotfixes.

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.
File nameFile versionFile sizeDateTimePlatform
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
For more 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
smtp ehlo 502 system.mail.smtpclient

Article ID: 913616 - Last Review: 12/09/2015 04:27:57 - Revision: 2.0

Microsoft .NET Framework 2.0, Microsoft Visual Studio 2005 Professional Edition, Microsoft Visual Studio 2005 Standard Edition

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