i found this question: Switch To Outlook Calendar using VSTO.
This works quite fine, but I want to open the Calendar in a new window to not change the users current window.
I could not find any information on how to do this, or if it is even possible. Thanks for any help!
Ok, I think I found it:
Explorer explorer = Globals.ThisAddIn.Application.GetNamespace("MAPI").GetDefaultFolder(OlDefaultFolders.olFolderCalendar).GetExplorer();
CalendarView calView = explorer.CurrentView;
calView.CalendarViewMode = OlCalendarViewMode.olCalendarViewWeek;
calView.GoToDate(date);
calView.Apply();
explorer.Activate();