Question

I am writing a COM add-in for Outlook using C#. If a meeting was saved and invitations were not sent, Outlook puts a message at the top of the form saying the invitations have not been sent. How do I determine programmatically that invitations have not been sent for a meeting?

I tried examining each Recipient and checking the MeetingResponseStatus. I would expect it to be OlResponseNone if the invitation has not been sent but OlResponseNotResponded if the invitations have been sent but no responses have been received. However, I always get OlResponseNone for recipients that either haven’t been sent an invitation or that have but have not yet reponded. I therefore can’t tell apart a meeting where invitations haven’t been sent from one where they have been sent but no one has responded.

I’ve done most of my testing in Outlook 2007, but I believe the same holds true for 2003 and 2010, all of which I need to support.

Answer 1

I found a partial answer in this post. I need to read the DASL property “http://schemas.microsoft.com/mapi/id/{00020329-0000-0000-C000-000000000046}/80BE0102”. In Outlook 2007 and leter, you can do this with a PropertyAccessor as follows:

appointment.PropertyAccessor.GetProperty("http://schemas.microsoft.com/mapi/id/{00020329-0000-0000-C000-000000000046}/80BE0102");

However, I need to also support Outlook 2003, and the PropertyAccessor property was added in Outlook 2007. I was therefore able to use Redemption’s RDOMail object with the following code (error handling omitted).

var _session = New RDOSession();
_session.Logon();
var _message = _session.GetMessageFromID(appointment.EntryID, ((Outlook.MAPIFolder)appointment.Parent).StoreID);
return (bool)_message.Fields["http://schemas.microsoft.com/mapi/id/{00062002-0000-0000-C000-000000000046}/8229000B"];
Marshal.ReleaseComObject(_message);
_session.Logoff();
Marshal.ReleaseComObject(_session);