Mit diesem Code geht es: using Microsoft.Office.Interop.Outlook; Microsoft.Office.Interop.Outlook.Application outlookApplication = new Microsoft.Office.Interop.Outlook.Application(); ; Microsoft.Office.Interop.Outlook.AppointmentItem appointmentItem = (Microsoft.Office.Interop.Outlook.AppointmentItem)outlookApplication.CreateItem(Microsoft.Office.Interop.Outlook.OlItemType.olAppointmentItem); appointmentItem.Subject = "Meeting Subject"; appointmentItem.Body = "The body of the meeting"; appointmentItem.Location = "Room #1"; appointmentItem.Start = DateTime.Now; appointmentItem.Recipients.Add("test@test.com"); appointmentItem.End = DateTime.Now.AddHours(1); appointmentItem.ReminderSet = true; appointmentItem.ReminderMinutesBeforeStart = 15; appointmentItem.Importance = Microsoft.Office.Interop.Outlook.OlImportance.olImportanceHigh; appointmentItem.BusyStatus = Microsoft.Office.Interop.Outlook.OlBusyStatus.olBusy; appointmentItem.Recipients.ResolveAll(); appointmentItem.Display(true);