Sending mail failure on VB.NET 2019

[pourkascheff]

Hi all,
I found this tutorial very easy and understandable. I followed it's instructions but following exception was thrown:


I turned off my email two-step verification but according to https://myaccount.google.com/lesssecureapps, this item is no longer supported.

Code for record:

Imports System.Net.Mail
Public Class Form2
    Private Sub SendBtn_Click(sender As Object, e As EventArgs) Handles SendBtn.Click
        Me.Cursor = Cursors.WaitCursor
        GroupBox1.Enabled = False
        Try
            Dim SMTP_SERVER As New SmtpClient
            Dim E_MAIL As New MailMessage
            SMTP_SERVER.UseDefaultCredentials = False
            SMTP_SERVER.Credentials = New Net.NetworkCredential(Usertxt.Text, Passtxt.Text)
            SMTP_SERVER.Port = 587
            SMTP_SERVER.EnableSsl = True
            SMTP_SERVER.Host = "smtp.gmail.com"
            E_MAIL = New MailMessage
            E_MAIL.From = New MailAddress(Usertxt.Text)
            E_MAIL.To.Add(Addresstxt.Text)
            E_MAIL.Subject = Subjecttxt.Text
            E_MAIL.IsBodyHtml = False
            E_MAIL.Body = Messagetxt.Text
            SMTP_SERVER.Send(E_MAIL)
            Me.Cursor = Cursors.Default
            GroupBox1.Enabled = True
            MsgBox("Successfully sent.", MsgBoxStyle.Information)
        Catch ex As Exception
            Me.Cursor = Cursors.Default
            MsgBox(ex.Message.ToString, MsgBoxStyle.Critical)
            GroupBox1.Enabled = True
            Addresstxt.Focus()
        End Try
    End Sub
End Class

- How can I rectify the matter?
- What does the 'server response was: 5.7.0' mean?