System.Net.Mail: Mail sent via Network delivery throws exception “Command not implemented/supported”

One of the customer reported that whenever he tries to send e-mail by using System.Net.Mail API they get the following error “System.Net.Mail.SmtpException error message: Command not implemented. The server response was: Command not Supported” I had a look at the application. They built a Microsoft Visual Studio 2005 based application and tried to send e-mail…

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