You certainly could write a macro to perform such cleanup after the import. See http://www.outlookcode.com/d/convertfields.htm for a basic script that shows how to loop through all the items in a folder and demonstrates basic Outlook property syntax.

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Sue Mosher, Outlook MVP
Author of Configuring Microsoft Outlook 2003
http://www.turtleflock.com/olconfig/index.htm
and Microsoft Outlook Programming - Jumpstart for
Administrators, Power Users, and Developers
http://www.outlookcode.com/jumpstart.aspx
> We are migrating from Notes to Exchange and using the tool provided by
> Lotus to export the personal address book into the Contacts in Outlook.
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>
> Hope that makes sense.