Actually UserProperties collection is really created on top of a special
blob that stores user propery definition. If a property is in the
UserProperties collection, there is guarantee that it will be actually have
a value (which is stored as a named MAPI property).
If you have a custom message class, UserProperties colelction will also
contain the custom properties associated with that form
(IMAPIFormInfo::CalcFormPropSet() on the Extended MAPI level), and, again,
it is not guaranteed that any particular property will actually be set on
the item.

--
Dmitry Streblechenko (MVP)
http://www.dimastr.com/
OutlookSpy - Outlook, CDO
and MAPI Developer Tool
-
"Ken Slovak - [MVP - Outlook]" wrote in message
...
1. UserProperties is a subset of ItemProperties, although you can only
add/remove UserProperties. You check that with the IsUserProperty Boolean
property. The ItemProperties collection is zero based, the count doesn't
start at 1, it starts at 0, unlike UserProperties which starts at 1.

2. Try it and see.

--
Ken Slovak
[MVP - Outlook]
http://www.slovaktech.com
Author: Professional Programming Outlook 2007.
Reminder Manager, Extended Reminders, Attachment Options.
http://www.slovaktech.com/products.htm


"Tadwick" wrote in message
...
1. Is the UserProperties collection simply a subset of ItemProperties?

2. When you send an AppointmentItem do UserProperty objects and
ItemProperty
objects get transferrred to the MeetingItem that arrives in the
recipient's
inbox?