从web.config发送带有凭据的电子邮件时出错

Question

I'm developing a website by ASP.NET MVC. I have this function in my IdentityConfig.cs :

public Task SendAsync(IdentityMessage message)
{
    SmtpClient client = new SmtpClient();
    var msg = new MailMessage();
    msg.From = new MailAddress("info@mywebsite.com");
    msg.To.Add(message.Destination);
    msg.Subject = message.Subject;
    msg.Body = message.Body;
    client.Host = "mywebsite.com";
    client.Port = 25; 
    client.Credentials = new
        System.Net.NetworkCredential("info@mywebsite.com", "mypassword");
    return client.SendMailAsync(msg);
}

I set up SMTP Service in IIS 8 and this function works fine. The problem is when I config SMTP credentials inside Web.config and try to send an email. MailSettings part of Web.config is as follows:

<system.net>
    <mailSettings>
      <smtp>
        <network host="mywebsite.com"
                 port="25" userName="info@mywebsite.com" password="mypassword" />
      </smtp>
    </mailSettings>
</system.net>

and the new SendAsync function is:

public Task SendAsync(IdentityMessage message)
{
    SmtpClient client = new SmtpClient();
    var msg = new MailMessage();
    msg.From = new MailAddress("info@mywebsite.com");
    msg.To.Add(message.Destination);
    msg.Subject = message.Subject;
    msg.Body = message.Body;
    return client.SendMailAsync(msg);
}

But when running this inside my controller, the following error occurs:

Bad sequence of commands. The server response was: This mail server requires authentication when attempting to send to a non-local e-mail address. Please check your mail client settings or contact your administrator to verify that the domain or address is defined for this server.

What could be the cause?

Answer 1

try adding defaultCredentials to false

  <network
          clientDomain="mywebsite.com"
          defaultCredentials="false"
          enableSsl="true"
          host="smtp.gmail.com"
          port="587"
          userName="sender@mywebsite.it" password="xxxxxxx"
        />

Note that for some servers (like gmail) the message.From needs to match with the username