Visual Basic.NET - CONFIRMACION DE LECTURA MAIL

Imports System.IO

Imports EASendMail   'se usa para enviar correos

Public Class Form1

    Private Sub Button1_Click_1(sender As Object, e As EventArgs) Handles Button1.Click

        Dim Mail As New SmtpMail("TryIt")

        Dim oSmtp As New SmtpClient()

        If TextBox1.Text = "" Then

            MsgBox("Agregar correo de destino")

        Else

            Try

                Mail.From = New MailAddress("correo que envia")

                Mail.To.Add(TextBox1.Text)

                Mail.Subject = (TextBox2.Text)

                Mail.TextBody = (RichTextBox1.Text)

                Mail.ReadReceipt = True

                Mail.DeliveryNotification = DeliveryNotificationOptions.OnFailure Or DeliveryNotificationOptions.OnSuccess

                'servidor de salida

                Dim servidor As New SmtpServer("smtp.office365.com")

                servidor.Port = 587

                servidor.ConnectType = SmtpConnectType.ConnectSSLAuto

                servidor.User = "correo"

                servidor.Password = "contraseña"

                If txtRuta.Text <> "" Then

                    Mail.AddAttachment(txtRuta.Text)

                End If

                Try

                    RichTextBox2.Text = "start to send email ..."

                    oSmtp.SendMail(servidor, Mail)

                    RichTextBox2.Text = "email was sent successfully!"

                Catch ex As Exception

                    MessageBox.Show(ex.Message.ToString, "Error", MessageBoxButtons.OK, MessageBoxIcon.Error)

                    RichTextBox2.Text = "failed to send email with the following error:"(ex.Message)

                End Try

            Catch ex As Exception

                MessageBox.Show(ex.Message.ToString, "Error", MessageBoxButtons.OK, MessageBoxIcon.Error)

            End Try

        End If

    End Sub

    Private Sub Button2_Click(sender As Object, e As EventArgs) Handles Button2.Click

        Try

            TextBox1.Clear()

            TextBox2.Clear()

            RichTextBox1.Clear()

            RichTextBox2.Clear()

        Catch ex As Exception

            MessageBox.Show(ex.Message.ToString, "Error", MessageBoxButtons.OK, MessageBoxIcon.Error)

        End Try

    End Sub

    Private Sub Button3_Click(sender As Object, e As EventArgs) Handles Button3.Click

        Try

            'La linea de abajo adjunta un archivo

            Me.OpenFileDialog1.ShowDialog()

            If Me.OpenFileDialog1.FileName <> "" Then

                txtRuta.Text = Me.OpenFileDialog1.FileName

            End If

            Dim nombreArchivo As String = Path.GetFileName(txtRuta.Text)

            LBnombreFile.Text = nombreArchivo

        Catch ex As Exception

            MessageBox.Show(ex.Message.ToString, "Error", MessageBoxButtons.OK, MessageBoxIcon.Error)

        End Try

    End Sub

End Class

Mail.ReadReceipt = True