Authentication Failed - SMTP Email

Question

Hello,

We are in the process of converting a VB6 project to .NET using VS2005. The problem is with sending the email. The error I am getting is the following:

System.Net.Mail.SmtpException: Syntax error, command unrecognized. The server response was: 5.7.0 Authentication failed
   at DCTEmail.Email.SendMail()
   at CustAdmin.frmEmail.btnSend_Click(Object sender, EventArgs e) in E:\SaberTooth.V4\SaberTooth\SaberTooth\Forms\System\frmEmail.vb:line 67

My code snippet looks as follows:

Try
     Dim Message As New MailMessage(SentFrom, SendTo, Subject, Body)
     Message.IsBodyHtml = False
     Dim MailClient As New SmtpClient
     MailClient.Host = strSMTPServerIP
     MailClient.Port = 25
     MailClient.UseDefaultCredentials = False
     MailClient.Credentials = New NetworkCredential(strSMTPUID, strSMTPPWD)
     MailClient.DeliveryMethod = SmtpDeliveryMethod.Network
     MailClient.Send(Message)
     MailClient = Nothing
     SendOK = True
Catch ex As Exception
     SendOK = False
     Throw ex
End Try

I am trying to send emails both internally and externally with the same results. We use Kerio Mail Server running on a Linux Box. I'm at my wits end. Apart from the obvious differences between VB6 and .NET, I can't explain why this is happening. I use IPWorks on the VB6 application. Can this be an issue with .NET?

Thanks for taking the time to help me.

Answer 1

I tried another server (SWBell) and the process worked fine. The problem does appear to be with Kerio. I contacted their support team. Here is the response they provided:

"The LOGIN SASL mechanism is obsoleted in favor of the PLAIN SASL mechanism. Clients SHOULD implement the PLAIN SASL mechanism and use it whenever offered by a server. The LOGIN SASL mechanism SHOULD NOT be used by a client when other plaintext mechanisms are offered by a server.

According to IETF draft (expired, obsolete), the server must send non-empty challenge first. Therefore, LOGIN authentication cannot use "initial-response" parameter.

Conclusion:

KMS DOES comply to RFC 2554. The client has a bug in SASL LOGIN mechanism implementation. Moreover, the client should use PLAIN instead of LOGIN."

I hope that helps explain why the script is having issues authenticating.

Anyone have any ideas on how to change to PLAIN instead of LOGIN?

Thanks

-- Val

Answer 2

Can you enable tracing using the steps discussed in

http://blogs.msdn.com/dgorti/archive/2005/09/18/471003.aspx

and send to [e-mail].

Also a netmon trace as outlined in http://blogs.msdn.com/dgorti/archive/2005/10/29/486887.aspx

will be helpful .

Thanks

Malar

 

 

Answer 3

Malar,

Email has been sent to [e-mail] along with trace file. Looking forward to your response.

-- Val

Answer 4

I got the same problem.

So what's the cure?

 

Thanks,

ffee

Answer 5

I have not been able to resolve the problem. I sent an email to Malar however have not heard anything. I suspect that it's a microsoft bug since I have the same program running using VB6 with and it works fine with the same server, user id and password.

I'll keep you posted if I find anything out.

 

Answer 6

Malar,

I never did hear back from you after my email. Any ideas? Would you like me to resend what I sent you originally?

Thanks

Answer 7

Please send it again. My machine crashed and I lost the emails..

 

 

 

Answer 8

Malar,

Just resent the file. to you via email.

Answer 9

I am getting the same error.

Please how should I get this working?

Answer 10

I also faced this. Will there be any comment from Microsoft?