I'm developing a custom form and I need lots of user-defined fields. What is
the best way for me to store these - as fields in the form or in a database
that the form reads and writes to?
How does Outlook store the fields anyway?
Outlook stores data in custom properties with the other data in each item. If you want users to be able to search on your fields and display them in views, you must use Outlook properties. If, on the other hand, "lots" means that you would have more than 32k of data per item (without counting the item body), then storing at least some data in a separate location would be an appropriate solution.

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Sue Mosher, Outlook MVP
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Microsoft Outlook Programming - Jumpstart for
Administrators, Power Users, and Developers
http://www.outlookcode.com/jumpstart.aspx
> I'm developing a custom form and I need lots of user-defined fields. What is
> the best way for me to store these - as fields in the form or in a database
> that the form reads and writes to?
>
> How does Outlook store the fields anyway?