无法通过允许Google访问安全性较低的应用程序和两步验证来解决问题

我已允许Google访问安全性较低的应用，但仍然遇到问题。 我什至尝试启用两步验证，但效果不佳。

Protected Sub sendMail_Click(sender As Object,e As EventArgs) Handles sendMail.Click
        Dim mainconn As String = System.Configuration.Configurationmanager.ConnectionStrings("user_ConnectionString").ConnectionString
        Dim con As New SqlConnection(mainconn)

        Dim query As String = "Select email,password from user_information where email = @email"
        Dim cmd As New SqlCommand
        cmd = New SqlCommand(query,con)

        cmd.Parameters.AddWithValue("@email",txtBoxEmailSupport.Text.Trim)
        con.Open()
        Dim sdr As SqlDataReader = cmd.ExecuteReader()


        If sdr.Read() Then

            Dim email_password As String = sdr("email").ToString.Trim
            Dim password_reset As String = sdr("password").ToString.Trim

            Dim mm As New MailMessage("jackieyong36@gmail.com",txtBoxEmailSupport.Text.Trim)
            mm.Subject = "Your forgotten Password!"
            mm.Body = String.Format("Smtp is working,man~~",email_password,password_reset)
            mm.IsBodyHtml = True
            Dim smtp As New SmtpClient()
            smtp.Host = "smtp.gmail.com"
            smtp.EnableSsl = True
            Dim nc As New NetworkCredential("jackieyong36gmail.com","12345")
            smtp.UseDefaultCredentials = True
            smtp.Credentials = nc
            smtp.Port = 587
            smtp.Send(mm)

            lblStatus.Text = "Your password has been sent to " + txtBoxEmailSupport.Text

        Else
            lblStatus.Text = "This email was not existed!"

        End If