Outlook Add-in - Application_ItemSend fired twice

Question

I'm writing an addin for Outlook that check if the appointment has been set between 13:30 to 14:30 and show the user a warning that he sent a meeting request between 13:30 to 14:00.

When someone sets a meeting in this time period it shows the message, but if for example he edits the meeting and removes one of the attendees, outlook asks if he wants to send the update only to the added or deleted attendees or if he wants to send the update to all of the attendees. Now, if he chooses to send the meeting to all of the attendees then the Application_ItemSend fired twice and he gets the warning message twice.

I tried to use the item.ForceUpdateToAllAttendees = true but it didn't help.

What is happening here? And how can I resolve this issue?

Answer 1

Would you not expect that if Outlook sends meeting cancelation to the deleted attendee and an update to the reaming attendees?