Gmail Error :The SMTP server requires a secure connection or the client was not authenticated. The server response was: 5.5.1 Authentication Required

Question

I am using following code to send email. The Code works correctly in my local Machine. But on Production server i am getting the error message

var fromAddres         


        

Answer 1

A comment from Tomasz Madeyski is what fixed my problem... he tells that exists a bug on SetDefaultCredential, him says:

"The issue is that in UseDefaultCredentials setter there is this code: this.transport.Credentials = value ? (ICredentialsByHost) CredentialCache.DefaultNetworkCredentials : (ICredentialsByHost) null; which overrides credentials set by Credentials setter. For me it looks like SmtpClient's bug"

if you put smtpClient.UseDefaultCredentials = false after set credentials... this line set to null those credentials...