Using System.Net.Mail vb08 help me pl@kz?!

Imports System.Net.Mail
Public Class Form1

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        'strings
        Dim smtpserver As New SmtpClient
        Dim mail As New MailMessage
        Dim username As String
        Dim password As String
        'username/password
        password = TextBox3.Text
        username = TextBox2.Text
        '@hotmail.com
        If ComboBox1.Text = "@hotmail.com" Then
            smtpserver.Credentials = New Net.NetworkCredential(username + ComboBox1.Text, password)
            smtpserver.Host = "smtp.live.com"
            smtpserver.Port = 25
            smtpserver.EnableSsl = True
            mail = New MailMessage
            mail.From = New MailAddress(username + ComboBox1.Text)
        End If
        If ComboBox1.Text = "@live.com" Then
            smtpserver.Credentials = New Net.NetworkCredential(username + ComboBox1.Text, password)
            smtpserver.Host = "smtp.live.com"
            smtpserver.Port = 25
            smtpserver.EnableSsl = True
            mail = New MailMessage
            mail.From = New MailAddress(username + ComboBox1.Text)
        End If
        If ComboBox1.Text = "@Gmail.com" Then
            smtpserver.Credentials = New Net.NetworkCredential(username + ComboBox1.Text, password)
            smtpserver.Host = "smtp.Gmail.com"
            smtpserver.Port = 587
            smtpserver.EnableSsl = True
            mail = New MailMessage
            mail.From = New MailAddress(username + ComboBox1.Text)
        End If
        mail.To.Add(TextBox5.Text)
        mail.Subject = TextBox4.Text
        mail.Body = TextBox1.Text
        smtpserver.Send(mail)
        'Msgbox
        MsgBox("Mail Sent")
end sub
end class