'делаем резервную копию писем
        Dim folder = _MailStorage
        MyZip(folder, u3 + Now.Date + ".zip")
        Try
            Dim email As New MailMessage
            Dim smtp As SmtpClient
            poluchatel = copy
            smtp = New SmtpClient(smtp1)
            smtp.Credentials = New Net.NetworkCredential(mail, parol)
            email.From = New MailAddress(mail)
            email.To.Add(New MailAddress(poluchatel))
            email.To.Add(New MailAddress(copy))
            email.Body = "Резервная копия входящих писем от " + CStr(Now.Date) + " для " + mail
            email.Subject = "Резервная копия входящих писем от " + CStr(Now.Date) + " для " + mail
            email.Attachments.Add(New System.Net.Mail.Attachment(u3 + Now.Date + ".zip"))
            smtp.Send(email)
            MsgBox("Резервная копия успешно создана!")
        Catch ex As Exception
            MsgBox("Ошибка! Отсутствует подключение к интернету!")
        End Try

Button1_click
checkfile(filename)
(***)
Private Function CheckFile(ByVal filename As String) As Boolean

Try
System.IO.File.Open(filename, IO.FileMode.Open, IO.FileAccess.Read, IO.FileShare.None)
FileClose(1)
Return False
Catch ex As Exception
Return True
End Try
End Function