Problem while sending Email

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VB

ASP.NET

I am converting the website from version 1.0 to 2.0.

In it there is a sending an email feature.

Previous namespace for sending email has changed.
I am adding a new namespace System.Net.Mail.MailMessage

For sending mail I got the failure sending smtp error.

What I do next:
Recently I installed windows server 2003 os.

My question: is it necessary to use smtp class and smtp server?
I want to check this operation locally, how to do?

My code is as follows. In this code the commented code is in version1.0 and without commented code in V2.0.
Please help me.

' Dim mm As New System.Web.Mail.MailMessage()
Dim mm As New System.Net.Mail.MailMessage
' mm.To = toaccount
mm.To.Add(New MailAddress(toaccount))
' mm.From = fromaccount
mm.From = New MailAddress(fromaccount)

mm.Subject = title
mm.Body = matter
'mm.Priority = MailPriority.High
' mm.BodyFormat = MailFormat.Html
mm.IsBodyHtml = True
' System.Web.Mail.SmtpMail.SmtpServer = "192.168.1.100"
Dim SmtpMail As New SmtpClient()
'good SmtpMail.Host = "192.168.1.100"
'SmtpMail.Host = "localhost "
'Dim s As New SmtpClient("192.168.1.108")
Try
    'System.Web.Mail.SmtpMail.Send(mm)
    SmtpMail.Send(mm)
    ' System.Net.Mail.SmtpClient(mm)
    ' s.Send(mm)
    Response.Write("Mail is sent successfully")
Catch ex As Exception
    Response.Write("The fpllowing exception occurred :" + ex.ToString())
    'check the InnerException
    While Not (ex.InnerException Is Nothing)
        Response.Write("-----------------------")
        Response.Write("The following InnerException reported: " + ex.InnerException.ToString)
        ex = ex.InnerException
    End While
End Try