Take a look at the new PropertyAccessor object in Outlook 2007. There are a number of articles in Help that explain how to use it to add custom properties, both those that can be visible to the user and those that aren't.

Sue Mosher, Outlook MVP
Author of Microsoft Outlook 2007 Programming:
Jumpstart for Power Users and Administrators
http://www.outlookcode.com/article.aspx?id=54

"Guy" <Guy@discussions.microsoft.com> wrote in message news:D67A6D42-C5D9-4247-BA80-5C45A989A822@microsoft.com...
> Sorry but a relative newbie when it comes to Outlook programming.
>
> Currently using Office 2007. From Access I create an appointment - A
> Delivery or Collection Docket - in a public Outlook folder using Automation.
> The docket (body of the appointment) contains information such as customer
> and delivery addresses, contact details including phone number, equipment to
> be
> delivered/collected, any special instructions and space for driver and
> customer signatures.
>
> The appointments/dockets are subsequently tracked by the van driver manager
> and printed using the default memo style by our van drivers.
>
> This all works fine, however, I would like to store private/hidden
> application data that isn't shown in the subject or body of the appointment
> (and therefore isn't easily modifiable by the user) such as the database
> table record id. Then at some point in the future I would like to loop though
> the Outlook appointments and retrieve this information to perform some
> additional KPI processing.
>
> Can you help?
>
> Guy
24 JunPrivate data in an appointment.Guy
24 Jun|- RE: Private data in an appointment.Guy
24 Jun\ Re: Private data in an appointment.Sue Mosher [MVP-Outlook]
24 Jun   \ Re: Private data in an appointment.Guy
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