Create an appointment in someone else's outlook calendar with C#

Question

I want to create a program which makes it possible to create an appointment in someone else's outlook calendar. For example : If someone asks their boss for five days free, their boss needs to be able to approve it and immediately make it visible in the person's outlook calendar. I already made some code in which allows you to set your own appointments. here is my code:

    public Form1()
    {
        InitializeComponent();

    }

    private void button1_Click(object sender, EventArgs e)
    {
        AddAppointment("ConferenceRoom #2345", "We will discuss progression the group project.", "Group Project", new DateTime(2016, 02, 23, 15, 30, 52), new DateTime(2016, 02, 23, 20, 30, 52));
    }
    private void AddAppointment(string location, string body, string subject, DateTime startdatum, DateTime einddatum)
    {
        try
        {
            var AppOutlook = new Outlook.Application();

            Outlook.AppointmentItem newAppointment =
            (Outlook.AppointmentItem)
            AppOutlook.CreateItem(Outlook.OlItemType.olAppointmentItem);
            newAppointment.Start = startdatum;
            newAppointment.End = einddatum;
            newAppointment.Location = location;
            newAppointment.Body = body;
            newAppointment.BusyStatus=Outlook.OlBusyStatus.olTentative;
            newAppointment.AllDayEvent = true;
            newAppointment.Subject = subject;
            newAppointment.Save();
            newAppointment.Display(true);
        }
        catch (Exception ex)
        {
            MessageBox.Show("The following error occurred: " + ex.Message);
        }
    }

PS: Sorry if my english isn't great.

Answer 1

I made use of the EWS api (https://msdn.microsoft.com/en-us/library/office/dd633710(v=exchg.80).aspx)

the code i used is:

try
        {
            ExchangeService service = new ExchangeService(ExchangeVersion.Exchange2007_SP1);
            service.UseDefaultCredentials = true;
            service.Credentials = new WebCredentials("[email protected]", "password");
            service.Url = new Uri("https://mail.domain.com/EWS/Exchange.asmx");
            service.ImpersonatedUserId = new ImpersonatedUserId(ConnectingIdType.SmtpAddress, "[email protected]");




            Appointment appointment = new Appointment(service);
            // Set the properties on the appointment object to create the appointment.
            appointment.Subject = "Tennis lesson";
            appointment.Body = "Focus on backhand this week.";
            appointment.Start = DateTime.Now.AddDays(2);
            appointment.End = appointment.Start.AddHours(1);
            appointment.Location = "Tennis club";
            appointment.ReminderDueBy = DateTime.Now;

            // Save the appointment to your calendar.
            appointment.Save(SendInvitationsMode.SendToNone);

            // Verify that the appointment was created by using the appointment's item ID.
            Item item = Item.Bind(service, appointment.Id, new PropertySet(ItemSchema.Subject));
        }
        catch (Exception ex)
        {
            MessageBox.Show(ex.Message);
        }