hello i am trying to send an email with yahoo. but i'm getting an error i dont understand, can someone plz help.. my code is bellow...

Code:
Imports System.Net.Mail

Public Class Form1

    Private Sub Button1_Click_1(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Try
            Dim mail As New MailMessage
            mail.Subject = subbox.Text
            mail.To.Add(toBox.Text)
            mail.From = New MailAddress(frombox)
            mail.Body = bodybox.Text 'is a richtextbox

            Dim SMTP As New SmtpClient("plus.smtp.yahoo.com)' i also tried "smtp.yahoo.com"
            SMTP.EnableSsl = True
            SMTP.Credentials = New System.Net.NetworkCredential(userbox.Text, passbox.Text)
            SMTP.Port = "465" ' i also tried "587"
            SMTP.Send(mail)
            MessageBox.Show("Message Sent")

        Catch ex As Exception
            MessageBox.Show("Error ", ex.Message)
        End Try
    End Sub