Outlook can import comma- and tab-delimited files through the File | IMport
and Export command.

Signature
Sue Mosher, Outlook MVP
Author of
Microsoft Outlook Programming - Jumpstart for
Administrators, Power Users, and Developers
http://www.outlookcode.com/jumpstart.aspx
>I need to import lots of email addresses into
> the Contacts in Outlook 2003 from one 'flat' file.
>
> The file contains only email adresses, separated
> by a semicolon, tab or some other character.