使用smtp傳送郵件是否有錯誤訊息可用？

以下是在網路中查詢到並可順利執行的smtp寄信程式, 但如果收件人信箱有誤或密碼等有誤, 程式仍會顯示 "finish" , 想請教眾高手, 如何獲得error message , smtp.Send(em)並不會傳回值. 先謝謝回覆者, 感謝

Try

        '***寫信***

        Dim em As Net.Mail.MailMessage = New Net.Mail.MailMessage()

        em.From = New Net.Mail.MailAddress("寄件信箱地址", "名稱", Encoding.UTF8)

        em.[To].Add(New Net.Mail.MailAddress("收件者信箱地址"))    '收件者

        em.Subject = "go"     '信件主題 

        em.SubjectEncoding = Encoding.UTF8

        em.Body = "ok"            '內容 

        em.BodyEncoding = Encoding.UTF8

        em.IsBodyHtml = True      '信件內容是否使用HTML格式

        '***寄信設定***

        Dim smtp As Net.Mail.SmtpClient = New Net.Mail.SmtpClient()

        '登入帳號認證

        smtp.Credentials = New Net.NetworkCredential("寄信信箱", "密碼")

        smtp.Port = 587 '465  

        smtp.EnableSsl = True   '啟動SSL 

        smtp.Host = "smtp-mail.outlook.com"   'SMTP伺服器

        'smtp.Host = "smtp.gmail.com"   'SMTP伺服器

        '***寄出***

        smtp.Send(em)

    Catch ex As Exception

        Result.text = ex.ToString()

    End Try

    'Result.text = "Finish"