title: C# SMTP fails to authenticate on Outlook.com, port 587. "The server response was: 5.7.1 Client was not authenticated"
body: <p>I'm attempting to send automated emails (genuinely required business reason - not spam!).  Code similar to that below used to work with another mail service provider but the customer has moved to &quot;outlook.com&quot; and they're now getting:</p>
  <pre><code>    The SMTP server requires a secure connection or the client was not authenticated. The server response was: 5.7.1 Client was not authenticated
  </code></pre>
  <p>Surely this (C#) code should work:</p>
  <pre><code>    private void Send_Click(object sender, EventArgs e)
      {
          MailMessage message = null;
          try
          {
              message = new MailMessage(From, To);
              message.Subject = &quot;Update Request Session from &quot; + From;
              message.CC.Add(Cc);
              message.Body = &quot;Test message: please ignore.&quot;;
              message.IsBodyHtml = false;
  
              SmtpClient client = new SmtpClient(&quot;smtp.outlook.com&quot;, 587);
              client.Credentials = new System.Net.NetworkCredential(From, Password);
              client.UseDefaultCredentials = false;
              client.DeliveryMethod = SmtpDeliveryMethod.Network;
              client.EnableSsl = true;
              
              client.Send(message);
          }
          catch (Exception ex)
          {
              Status.Text = ex.Message;
          }
          
          if (message != null)
          {
              message.Dispose();
          }
      }
  </code></pre>
  <p>Please note the DeliveryMethod and EnableSsl are being set and that the port is 587.</p>
  <p>I've created another test account on my Outlook client (the desktop program, not the web service) to test the parameters which the code above uses:</p>
  <ul>
  <li>user name</li>
  <li>password</li>
  <li>smtp.outlook.com</li>
  <li>587</li>
  <li>TLS</li>
  </ul>
  <p>and the &quot;Test Account Settings&quot; in Outlook shows that the parameters are correct (&quot;Task: Send test e-mail message - Status:Completed&quot;).  So I think the user name and password must be correct.</p>
  <p>I've turned on verbose logging on as described here: <a href="http://social.msdn.microsoft.com/Forums/en-US/netfxnetcom/thread/28b5a576-0da2-42c9-8de3-f2bd1f30ded4/" rel="nofollow noreferrer">http://social.msdn.microsoft.com/Forums/en-US/netfxnetcom/thread/28b5a576-0da2-42c9-8de3-f2bd1f30ded4/</a>.  This has produced a plenty of output, too much to post here.  Here are the last few lines:</p>
  <pre><code>System.Net Information: 0 : [6312] SecureChannel#28756230 - Remote certificate was verified as valid by the user.
  System.Net.Sockets Verbose: 0 : [6312] Socket#59109011::Send()
  System.Net.Sockets Verbose: 0 : [6312] Data from Socket#59109011::Send
  System.Net.Sockets Verbose: 0 : [6312] 00000000 : 17 03 01 00 30 4B BC 72-D3 A8 D7 EC FB 3C 21 0F : ....0K.r.....&lt;!.
  System.Net.Sockets Verbose: 0 : [6312] 00000010 : D7 BA A2 1F 72 1D D0 E6-4B DB 9A EC 9E 70 FD BC : ....r...K....p..
  System.Net.Sockets Verbose: 0 : [6312] 00000020 : 73 B9 CC 6A 11 9E 32 E0-B2 47 D7 35 C0 BA CD DE : s..j..2..G.5....
  System.Net.Sockets Verbose: 0 : [6312] 00000030 : 38 CA F6 93 8E                                  : 8....
  System.Net.Sockets Verbose: 0 : [6312] Exiting Socket#59109011::Send()  -&gt; 53#53
  System.Net.Sockets Verbose: 0 : [6312] Socket#59109011::Receive()
  System.Net.Sockets Verbose: 0 : [6312] Data from Socket#59109011::Receive
  System.Net.Sockets Verbose: 0 : [6312] 00000000 : 17 03 01 00 D0                                  : .....
  System.Net.Sockets Verbose: 0 : [6312] Exiting Socket#59109011::Receive()   -&gt; 5#5
  System.Net.Sockets Verbose: 0 : [6312] Socket#59109011::Receive()
  System.Net.Sockets Verbose: 0 : [6312] Data from Socket#59109011::Receive
  System.Net.Sockets Verbose: 0 : [6312] 00000005 : 4D 6F 22 3C B8 A4 39 14-B0 FC B9 58 23 9A 26 70 : Mo&quot;&lt;..9....X#.&amp;p
  System.Net.Sockets Verbose: 0 : [6312] 00000015 : 89 52 B4 E1 8D 74 D6 23-5C 2B 7C 44 6E EB 1A F7 : .R...t.#\+|Dn...
  System.Net.Sockets Verbose: 0 : [6312] 00000025 : 7A 56 3D 18 0E 93 9C C5-C6 43 28 25 AA 3D DF 89 : zV=......C(%.=..
  System.Net.Sockets Verbose: 0 : [6312] 00000035 : 46 78 9B 69 ED FA 51 65-29 D9 DF A6 3F 9F 9F 25 : Fx.i..Qe)...?..%
  System.Net.Sockets Verbose: 0 : [6312] 00000045 : 22 18 99 13 6A AA FB 49-BE 9C 53 F2 96 3C 5A 5A : &quot;...j..I..S..&lt;ZZ
  System.Net.Sockets Verbose: 0 : [6312] 00000055 : 60 E1 23 FA CA 92 B9 4A-75 9D 87 D5 66 4D FB 84 : `.#....Ju...fM..
  System.Net.Sockets Verbose: 0 : [6312] 00000065 : 99 63 D1 27 C9 41 90 C8-3D BE 82 E6 A2 62 EB 56 : .c.'.A..=....b.V
  System.Net.Sockets Verbose: 0 : [6312] 00000075 : 5E D0 ED 67 B3 67 FD 6A-B0 99 34 07 DA 88 3D 02 : ^..g.g.j..4...=.
  System.Net.Sockets Verbose: 0 : [6312] 00000085 : 2E E6 E5 DB 4F E7 C0 EF-A9 AD 01 C0 5D FE 94 19 : ....O.......]...
  System.Net.Sockets Verbose: 0 : [6312] 00000095 : 92 0A 0E 6F C3 C7 F5 62-E4 15 F2 6D 56 A4 5B 74 : ...o...b...mV.[t
  System.Net.Sockets Verbose: 0 : [6312] 000000A5 : C0 7A 2F 16 A7 F2 C0 F8-F4 90 00 EB DB 52 90 85 : .z/..........R..
  System.Net.Sockets Verbose: 0 : [6312] 000000B5 : ED FA C6 91 5A 32 49 4A-9F F9 1D 11 62 97 C7 DC : ....Z2IJ....b...
  System.Net.Sockets Verbose: 0 : [6312] 000000C5 : 96 11 67 E0 95 D2 95 0C-D9 41 C9 81 F8 4C 58 0F : ..g......A...LX.
  System.Net.Sockets Verbose: 0 : [6312] Exiting Socket#59109011::Receive()   -&gt; 208#208
  System.Net.Sockets Verbose: 0 : [6312] Socket#59109011::Send()
  System.Net.Sockets Verbose: 0 : [6312] Data from Socket#59109011::Send
  System.Net.Sockets Verbose: 0 : [6312] 00000000 : 17 03 01 00 40 45 FD 20-1F 27 A1 B3 50 A3 99 5D : ....@E. .'..P..]
  System.Net.Sockets Verbose: 0 : [6312] 00000010 : F3 DA 03 7E 47 C4 8C 91-21 7F 25 7C 09 CC E4 68 : ...~G...!.%|...h
  System.Net.Sockets Verbose: 0 : [6312] 00000020 : 27 95 BE C7 FB 9E BC 65-67 64 CE C7 BE 4A BB 48 : '......egd...J.H
  System.Net.Sockets Verbose: 0 : [6312] 00000030 : 89 36 A4 A4 90 B4 7B B4-C0 B5 DB 5B 18 3F 4A C3 : .6....{....[.?J.
  System.Net.Sockets Verbose: 0 : [6312] 00000040 : A2 DB 51 B5 46                                  : ..Q.F
  System.Net.Sockets Verbose: 0 : [6312] Exiting Socket#59109011::Send()  -&gt; 69#69
  System.Net.Sockets Verbose: 0 : [6312] Socket#59109011::Receive()
  System.Net.Sockets Verbose: 0 : [6312] Data from Socket#59109011::Receive
  System.Net.Sockets Verbose: 0 : [6312] 00000000 : 17 03 01 00 40                                  : ....@
  System.Net.Sockets Verbose: 0 : [6312] Exiting Socket#59109011::Receive()   -&gt; 5#5
  System.Net.Sockets Verbose: 0 : [6312] Socket#59109011::Receive()
  System.Net.Sockets Verbose: 0 : [6312] Data from Socket#59109011::Receive
  System.Net.Sockets Verbose: 0 : [6312] 00000005 : 43 8E E7 44 71 B3 84 BC-5F 08 39 CE B1 3A A4 F9 : C..Dq..._.9..:..
  System.Net.Sockets Verbose: 0 : [6312] 00000015 : F4 92 BE B3 D7 10 81 14-B9 5B BA E3 35 93 34 12 : .........[..5.4.
  System.Net.Sockets Verbose: 0 : [6312] 00000025 : AF 32 F1 69 82 BD B9 8B-4C 2F 47 5F 8B 95 7E 52 : .2.i....L/G_..~R
  System.Net.Sockets Verbose: 0 : [6312] 00000035 : 94 4C A6 79 6A F6 E2 84-D1 9E A5 D3 16 98 44 E1 : .L.yj.........D.
  System.Net.Sockets Verbose: 0 : [6312] Exiting Socket#59109011::Receive()   -&gt; 64#64
  System.Net Error: 0 : [6312] Exception in the SmtpClient#44419000::Send - The SMTP server requires a secure connection or the client was not authenticated. The server response was: 5.7.1 Client was not authenticated
  System.Net Error: 0 : [6312]    at     System.Net.Mail.MailCommand.CheckResponse(SmtpStatusCode statusCode, String response)
     at     System.Net.Mail.MailCommand.Send(SmtpConnection conn, Byte[] command, String from)
     at     System.Net.Mail.SmtpTransport.SendMail(MailAddress sender, MailAddressCollection recipients, String deliveryNotify, SmtpFailedRecipientException&amp; exception)
     at     System.Net.Mail.SmtpClient.Send(MailMessage message)
  System.Net.Sockets Verbose: 0 : [6312] Socket#59109011::Dispose()
  System.Net Verbose: 0 : [6312] Exiting SmtpClient#44419000::Send() 
  </code></pre>
  <p>The first of those lines suggests to me that the SmtpClient and outlook.com have agreed on the encryption protocols to use, but the rest of it is means little to me bar the &quot;5.7.1 Client was not authenticated&quot; line.</p>
  <p>Has anyone run into similar problems connecting to Outlook.com?</p>
  <p>Thanks in advance.</p>
  <p>Ross</p>