'!!! кодVB6
Option Explicit

Private Sub Command1_Click()
  SendTestMailCDO
End Sub

Private Sub SendTestMailCDO()
  Const email_To As String = "recipient@bk.ru"
  Const email_From As String = "sender@gmail.com"
  Const smtp_Server As String = "smtp.gmail.com"
  Const smtp_Username As String = "sender@gmail.com"
  Const smtp_Password As String = "password"

  Dim o_Mess As CDO.Message 'As Object
  Dim v_Conf As String
  
  '-------------------------------
  'composing message with CDO
  On Error GoTo ErrOfSend
  Set o_Mess = CreateObject("CDO.Message")
  v_Conf = "http://schemas.microsoft.com/cdo/configuration/"
  With o_Mess
    .To = email_To
    .From = email_From
    .Subject = "Test subject"
    .TextBody = "Test body"
    '.AddAttachment Trim(TextAttach.Text)
    With .Configuration.Fields
      .Item(v_Conf & "sendusing") = 2
      .Item(v_Conf & "smtpserver") = smtp_Server
      .Item(v_Conf & "smtpauthenticate") = 1 '1-использовать
      .Item(v_Conf & "sendusername") = smtp_Username
      .Item(v_Conf & "sendpassword") = smtp_Password
      .Item(v_Conf & "smtpserverport") = "465"
      .Item(v_Conf & "smtpusessl") = True 'использовать SSL
      .Item(v_Conf & "smtpconnectiontimeout") = 60 'пока считаем что 60, потом м.б. добавим параметр
      .Update
    End With
    .Send
  End With
  MsgBox "Пробное сообщение на адрес " & o_Mess.To & " было успешно отправлено!", vbInformation + vbOKOnly, "Email отправлен"
  Exit Sub
ErrOfSend:
  MsgBox "Отправка письма завершилась неудачей." & vbCrLf & "Код ошибки: " & Err.Number & vbCrLf & Err.Description, _
   vbCritical + vbOKOnly, "Отправка email не удалась."
End Sub

  Private Sub ButtonWebMail_Click(sender As Object, e As EventArgs) Handles ButtonWebMail.Click
    Try
      Dim Message As System.Web.Mail.MailMessage = New System.Web.Mail.MailMessage()
      Dim v_Conf As String = "http://schemas.microsoft.com/cdo/configuration/"
      With Message
        .To = "Получатель<recipient@bk.ru>;"
        .From = "Отправитель<sender@gmail.com>;"
        .Subject = "Тема сообщения"
        .Body = "Текст сообщения"
        .BodyFormat = Web.Mail.MailFormat.Text
        .BodyEncoding = System.Text.Encoding.UTF8
        .Attachments.Add(New Web.Mail.MailAttachment(IO.Path.Combine(Application.StartupPath, "readme.txt")))
        With .Fields
          .Item(v_Conf & "sendusing") = 2
          .Item(v_Conf & "smtpserver") = "smtp.gmail.com"
          .Item(v_Conf & "smtpserverport") = 465
          .Item(v_Conf & "smtpauthenticate") = 1 '1-использовать
          .Item(v_Conf & "sendusername") = "sender@gmail.com"
          .Item(v_Conf & "sendpassword") = "password"
          .Item(v_Conf & "smtpusessl") = True 'использовать SSL
          .Item(v_Conf & "smtpconnectiontimeout") = 60 'пока считаем что 60, потом м.б. добавим параметр
        End With
      End With
      Web.Mail.SmtpMail.SmtpServer = "smtp.gmail.com"
      Web.Mail.SmtpMail.Send(Message)
      MsgBox("Test mail was sent successfully!", vbInformation + vbOKOnly, "Email was sent")
    Catch
      MsgBox("Sending mail...Failed." & vbCrLf & "Error code: " & Err.Number & vbCrLf & Err.Description, _
       vbCritical + vbOKOnly, "Sending mail failed.")
    End Try
  End Sub