Net Credentials des aktuellen Nutzers

 Dim myMsg As New MailMessage
            myMsg.From = New MailAddress("yyyyy@xxxxx.com")  
            myMsg.To.Add("Test@test.com")  
            myMsg.Subject = "Betreff TEST 2  Office365  16-22"  
            myMsg.Body = "Inhalt TEST Office365  16-22"  
            myMsg.IsBodyHtml = False

            Dim mySmtpClient As New SmtpClient()
            mySmtpClient.Host = "smtp.office365.com" '  
            mySmtpClient.Port = 587
            mySmtpClient.EnableSsl = True
            mySmtpClient.UseDefaultCredentials = True

            mySmtpClient.Send(myMsg)

Dim mySmtpClient As New SmtpClient()
            mySmtpClient.Host = "smtp.office365.com" '  
            mySmtpClient.Port = 587
            mySmtpClient.EnableSsl = True
            mySmtpClient.Credentials = New System.Net.NetworkCredential("yyyyy@xxxxx.com", "zzzzzzz")  
            mySmtpClient.Send(myMsg)

        Dim myService As New ExchangeService()

        myService.Url = New Uri("https://outlook.office365.com/EWS/Exchange.asmx")  
        myService.PreAuthenticate = True
        myService.UseDefaultCredentials = True
        myService.AutodiscoverUrl("username@domain.com")  

        Dim message As New EmailMessage(myService)

        message.Subject = "TEST 4"  
        message.Body = "bnnbnnb"  
        message.ToRecipients.Add("Testr@yyyyy.info")  
        message.ToRecipients.Add("Teste@xxxx.com")  
        message.Save()
        message.SendAndSaveCopy()

        Public Function RedirectionUrlValidation(ByVal url As String) As Boolean
              Dim redirectionValidated As Boolean = False
              Dim redirectionUri As Uri = New Uri(url)
              If redirectionUri.Scheme = "https" Then redirectionValidated = True  
              If url.Equals("https://autodiscover-s.outlook.com/autodiscover/autodiscover.xml") Then redirectionValidated = True  
        Return redirectionValidated
    End Function