Automatically creating entry in Outlook calendar using the Exchange API - calendar

Question

I am using the Exchange API to send appointment requests from any email address. Below is my code:
ExchangeService exService = new ExchangeService(ExchangeVersion.Exchange2013);
exService.Url = new Uri("exchange URL");
exService.Credentials = new WebCredentials("userID", "password");
Appointment appointment = new Appointment(exService);
appointment.Subject = "Test Subject";
appointment.Body = "test body";
appointment.Location = "Location";
appointment.Start = <Meeting start time>;
appointment.End = <Meeting end time>
appointment.RequiredAttendees.Add("abc#xyz.com");
appointment.Save(SendInvitationsMode.SendOnlyToAll);
This code is working fine: it sends an invitation email to the attendee.
What I want to know is, is it possible to make an entry into the attendee's Outlook calendar directly, without any invitation email or any approval from the attendee?

Answer 1

No, but if you impersonate the Attendee you can then accept the invitation on their behalf. See:
https://msdn.microsoft.com/en-us/library/office/dd633680(v=exchg.80).aspx
https://msdn.microsoft.com/en-us/library/office/dd633648(v=exchg.80).aspx

Answer 2

Below code might help you.
ExchangeService exService = new ExchangeService(ExchangeVersion.Exchange2013);
exService.Url = new Uri("exchange URL");
exService.Credentials = new WebCredentials("userID", "password");
Collection<Appointment> Meetings = new Collection<Appointment>();
Appointment appointment = new Appointment(exService);
appointment.Subject = "Test Subject";
appointment.Body = "test body";
appointment.Location = "Location";
appointment.Start = <Meeting start time>;
appointment.End = <Meeting end time>
appointment.RequiredAttendees.Add("abc#xyz.com");
Meetings.add(appointment)
ServiceResponseCollection<ServiceResponse> responses = service.CreateItems(Meetings,WellKnownFolderName.Calendar,MessageDisposition.SendOnly,SendInvitationsMode.SendToNone);