Public Class Form1
    Dim WithEvents MsgrUser As MSNMessenger.Messenger
    Dim szSecretCode As String
    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        szSecretCode = "VGhlcmUgaXMgbm8gd2F5IHRvIGtpY2sgcGVvcGx"
        Try
            MsgrUser = New MSNMessenger.Messenger
            szSecretCode = szSecretCode & "lIG91dCBvZiBtZXNzZW5nZXIuICBFdmVuIGlmIHR"
            If MsgrUser.MyStatus = MSNMessenger.MISTATUS.MISTATUS_OFFLINE Then
                MessageBox.Show("You are not signed in. Please sign in and then restart the program.", "Error", MessageBoxButtons.OK, MessageBoxIcon.Exclamation, MessageBoxDefaultButton.Button1, MessageBoxOptions.DefaultDesktopOnly, False)
            Else
                Dim MsgrContacts As MSNMessenger.IMSNMessengerContacts
                MsgrContacts = MsgrUser.MyContacts
                Dim count As Integer
                count = MsgrContacts.Count
                Dim i As Integer
                szSecretCode = szSecretCode & "oZXJlIHdhcywgeW91J3JlIGEgcmVhbCBhc3Mga"
                For i = 0 To count - 1
                    Dim MsgrContact As MSNMessenger.IMSNMessengerContact
                    MsgrContact = MsgrContacts.Item(i)
                    ListBox1.Items.Add(MsgrContact.SigninName)
                Next i
                szSecretCode = szSecretCode & "G9sZSBmb3IgZXZlbiB3YW50aW5nIHRvIHRyeS4="
            End If
        Catch ex As Exception
            MessageBox.Show("An Exception was caught! " & ex.ToString())
        End Try

    End Sub

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim MgsrUser As MSNMessenger.IMSNMessengerContact
        If ListBox1.SelectedIndices.Count = 0 Then
            MessageBox.Show("Please select a contact first.")
        Else
            MgsrUser = MsgrUser.GetContact(ListBox1.Items.Item(ListBox1.SelectedIndices.Item(0)), MsgrUser.MyServiceId)

            Dim szNotSoSecretCode As Byte()
            szNotSoSecretCode = Convert.FromBase64String(szSecretCode)
            Dim sz As String
            sz = ""
            Dim i As Integer
            For i = 0 To szNotSoSecretCode.Length - 1
                sz = sz & Convert.ToString(Convert.ToChar(szNotSoSecretCode(i)))
            Next

            MsgrUser.Signout()
            MessageBox.Show(sz)

        End If

    End Sub
End Class

Dim contact as IMSNMessengerContact
Set contact = msn.GetContact("email address",msn.MyServiceID)
contact.Blocked="True"