To convert imported data to custom fields
Outlook allows you to import data directly only to built-in
forms, not custom forms. Importing
directly to custom forms takes code or a third-party tool. An
alternative is to import to a built-in form, using
the fields provided for that form, then convert the
items to use your custom form and custom fields.
This Outlook VBA code sample, for
Contact items, does both. It converts data imported to the built-in
User1, User2, User3, and User4 properties to four user-defined
properties present in a custom form. Run it after you have imported the data.