Not possible, not least becasue Outlook has no concept of "opening" an
account.

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Sue Mosher, Outlook MVP
Author of
Microsoft Outlook Programming - Jumpstart for
Administrators, Power Users, and Developers
http://www.outlookcode.com/jumpstart.aspx
> How do I create different contacts per email account on a single computer?
> I
> am using Outlook 2003 and have 4 different email accounts, and want a
> different Address Book (Contacts) to display when each account is opened.