title: Mailbox unavailable. The server response was: No such user here
body: <p>I am using the below code in web.config and the email is sent to my gmail account without any problem. But when i am trying to send the same email to mycompany email, I get the error " System.Net.Mail.SmtpFailedRecipientException: Mailbox unavailable. The server response was: No such user here". But i very much have the mailbox . Is there something i am missing?? Please advice me!! Thank you very much in advance!! </p>
  
  <p>This is in new IIS 7.5 using ASP.net application. </p>
  
  <pre><code>&lt;system.net&gt;
      &lt;mailSettings&gt;
          &lt;smtp deliveryMethod="Network"&gt;
              &lt;network host="localhost" port="25" defaultCredentials="true" clientDomain="" /&gt;
          &lt;/smtp&gt;
      &lt;/mailSettings&gt;
  &lt;/system.net&gt;
  </code></pre>
  
  <p>In asp.net</p>
  
  <pre><code>SmtpClient smtp = new SmtpClient();
  smtp.Send(message);
  </code></pre>