The SMTP server requires a secure connection or the client was not authenticated.

[praveenb000]

i write code for sending mail to client's given email addresses.

But Im getting following error message

The SMTP server requires a secure connection or the client was not authenticated. The server response was: dnsgem.org ESMTP MailEnable Service, Version: 0--2.53 denied access at 09/30/09 08:49:39


this is the code i written for sending mail

    Public Sub SendMail(ByVal Efrom As String, ByVal EReceiver As String, ByVal subject As String, ByVal body As String, ByVal attachmentFileName As String)

 Try

            Dim ToAddress As String

            ToAddress = "kitsinda@gmail.com"

            Dim Msg1 As New MailMessage(Efrom, ToAddress)
            Msg1.Subject = subject
            Msg1.Body = body
            Msg1.Priority = MailPriority.Normal
            Msg1.IsBodyHtml = True

            If (attachmentFileName <> "") Then
                Msg1.Attachments.Add(New Attachment(attachmentFileName))
            End If

            Dim client1 As New SmtpClient(SMTPSERVER, 25)
            client1.Credentials = New System.Net.NetworkCredential(Me.MailUsername, Me.MailPassword)
            client1.Send(Msg1)
 Catch ex As SmtpException
            Throw New Exception(ex.Message)

        Finally

        End Try

End Sub

I don't know where i made mistake.

this is the url for

http://kitseducation.n et/innerpages/enquiry.aspx,

Please give me solution for the above problem

Thanks In Advance.

[Frinavale]

You need to contact the company hosting the SMTP server and find out what port to connect on.

Right now you're connecting on the default port (25) but from my experience secured SMTP servers don't use this port.

-Frinny

[blck]

Hi praveenb000,

I also have the problem. Do you solved? Can you help me.

[PsychoCoder]

You need to use the proper port (looks like you're sending it to GMail) so add this to your SmtpClient:

Dim client1 As new SmtpClient("smtp.gmail.com");
client1.Port = 587;
client1.Credentials = new System.Net.NetworkCredential("myaccount@gmail.com", "mypass");
client1.EnableSsl = true;

[Frinavale]

I included a code snippet for how to send an email through gmail in the Quick reference on how to send an email using .NET article.

:)

-Frinny

[blck]

Hi,

I tried however it aslo display error: The SMTP server requires a secure connection or the client was not authenticated. The server response was: host5.vdconline .vn ESMTP MailEnable Service, Version: 5.51-- denied access at 02/04/12 04:08:41

My code:

MailMessage msg = new MailMessage();
        SmtpClient smtp = new SmtpClient("*.*.*.*", 25);        
        msg.From = new MailAddress("admin@***");        
        msg.To.Add(new MailAddress(TextBox1.Text));
        msg.Subject = "Recover password";
        msg.Body = "";
        msg.IsBodyHtml = true;        
                        
        smtp.DeliveryMethod = SmtpDeliveryMethod.Network;        

        smtp.EnableSsl = true;  

        smtp.UseDefaultCredentials = false;
        smtp.Credentials = new NetworkCredential("admin@***", "*****");              
try
        {
            smtp.Send(msg);
            Label3.Text = "Email sent successfully";
        }
        catch (Exception ex)
        {
            Label3.Text = ""+ex.Message;
        }

Please help me!
Thanks in advance!

[PsychoCoder]

For starters you're still using port 25, GMail requires port 587. Given the last part of the error message it's saying you're using the wrong username/password combination.

Are you sending email through Gmail or a different host?

[blck]

Hi,

I checked all info. Username and password of my webmail are correct.
I rented a host. Port outgoing of host is 25.
Particularly, before hosting, I sended email from this host to my gmail by control from my computer. It is successful. However, after hosting, it has error. I don't understand.
Alternatively, I sended email through gmail. It is successful.

Please help me! Thanks.