SMTP - because the target machine actively refused it

You'll need to check with your hosting company and see what mail server you should use.

Some hosting companies require you send to "smtp.domain.com", with SMTP authentication, some require you send to "localhost".

I have worked with the hosting company and they have given me the mail server, and told me it's authenticated, I am using the following script for that part:

Dim smtp As New SmtpClient("67.15.97.8")
smtp.Credentials = New NetworkCredential("username", "password")
smtp.Port = 23 'I have tried it with and without this line, as well as port 587
smtp.Send(objMail)

Is there a way I can test this on a dev smtp server on my machine? I am using VS2008 and their temporary web server that creates itself when you hit view in browser. I assume this doesn't have an smtp element to it. Therefore do I have to install the full IIS with smtp element (Win XP) if I wanted to test this on my local machine - or would that not still work. At least then I guess we could rule out the code or anything my end.

If you are using that IP, and smtp authentication, you can test it from anywhere.  You are using the wrong port though, 23 is telnet, 25 is SMTP.  If you don't assign a port it defaults to port 25.

Also, you may want to set UseDefaultCredentials to false though, something like this.

Dim smtp As New SmtpClient("67.15.97.8")
smtp.UseDefaultCredentials = False
smtp.Credentials = New NetworkCredential("username", "password")

Also you can use a Try/Catch block on the Send to catch errors.

Try
    smtp.Send(objMail)
Catch ex As Exception
    'send error to a label or something ex.:
    'Label1.Text = "Error: " & ex.Message
End Try

Ok, I seem to be a little bit closer now.  I no longer get the error above, but the emails are not getting through. My ISP test a page in asp and their's works, see below. Mine is asp.net but I am hoping someone will spot the difference as they are pretty simple scripts.

My script now says that it has gone through (at least it doesn't produce an error like  before), but no emails arrive. I test the ISP script straight after, and then arrive. Most anoying! lol.

    Sub Send2Mail(ByVal sender As Object, ByVal e As EventArgs)
 
        Try
            Dim objMail As New MailMessage()
 
            objMail.To.Add("test@test.com")
            objMail.From = New MailAddress(strEmail.Text)
 
            objMail.Priority = MailPriority.Normal
            objMail.Subject = strSubject.Text
            objMail.IsBodyHtml = False
 
            objMail.Body = "Name : " + strName.Text + vbNewLine + "Email : " + strEmail.Text + vbNewLine + "Message : " + strYourMsg.Text
 
            Dim smtp As New SmtpClient("xx.xx.xx.xx")
            smtp.Port = "25"
            smtp.UseDefaultCredentials = False
            smtp.Send(objMail)
 
            strMessage.Text = "<p id='feedback'>- Thanks for your kind message.</p>"
            feedbackForm.Visible = False
 
        Catch ex As Exception
            strMessage.Text = "<p id='feedback'>- Error: " & ex.Message & "</p>"
 
        End Try
 
    End Sub
 
ISO scrip in asp:
 
<%
Set objMessage = CreateObject("CDO.Message") 
objMessage.Subject = "Example CDO Message" 
objMessage.From = "tester@test.com" 
objMessage.To = "test@test.com" 
objMessage.TextBody = "cdo message"
 
'==This section provides the configuration information for the remote SMTP server.
'==Normally you will only change the server name or IP.
objMessage.Configuration.Fields.Item _
("http://schemas.microsoft.com/cdo/configuration/sendusing") = 2 
 
'Name or IP of Remote SMTP Server
objMessage.Configuration.Fields.Item _
("http://schemas.microsoft.com/cdo/configuration/smtpserver") = "xx.xx.xx.x"
 
'Server port (typically 25)
objMessage.Configuration.Fields.Item _
("http://schemas.microsoft.com/cdo/configuration/smtpserverport") = 25 
 
objMessage.Configuration.Fields.Update
 
'==End remote SMTP server configuration section==
 
objMessage.Send
If Err <> 0 Then 
	Response.Write "An error occurred: " & Err.Description 
else
	Response.Write "Successfully Sent"
End If 
%>

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Oh dear, the silence isn't looking good.

You have this: objMail.From = New MailAddress(strEmail.Text)

Their server may only allow "From" addresses from local email accounts on their email server, since they are not using SMTP auth.

If you want to be able to reply to a user that sends an email, just add this.

objMail.From = New MailAddress"tester@test.com")
objMail.ReplyTo = New MailAddress(strEmail.Text)