title: Mailbox unavailable. The server response was: 5.4.1 Relay Access Denied
body: <p>I am getting "Mailbox unavailable. The server response was: 5.4.1 Unable to relay for myemail@mydomain.com" when I try to send the mail using C# code. </p>
  
  <p>Then I tested my smtp server <a href="https://www.wormly.com/test_smtp_server" rel="nofollow">here</a>. </p>
  
  <p>Here when I enter my smtp server, sender and recipient name. I got followoing message:</p>
  
  <blockquote>
    <p>MAIL FROM: mymail@mydomain.com</p>
    
    <p>SMTP -> FROM SERVER:</p>
    
    <p>250 2.1.0 Sender OK</p>
    
    <p>RCPT TO: anothermail@mydomain.com</p>
    
    <p>SMTP -> FROM SERVER:</p>
    
    <p>550 5.4.1 Relay Access Denied</p>
    
    <p>SMTP -> ERROR: RCPT not accepted from server: 550 5.4.1 Relay Access
    Denied</p>
  </blockquote>
  
  <p>Message sending failed.</p>