Hi

you can try to use the event handler that fires when you send an item. Because when you accept a meeting you send an item. So you first check if it is a meeting request and if so you run your code.

like this

Private Sub Application_ItemSend(ByVal Item As Object, Cancel As Boolean)

If InStr(Item.MessageClass, "IPM.Schedule.Meeting.Request") > 0 Then
'do your thing here

end if
end sub