There are two relevant things you should know on this issue. The first is
290684 OL2002: The Save Password Setting Is Not Saved When You Connect to a
Then: You can force the credentials that Outlook will use by prompting for
To prompt for credentials using Outlook 2002:
1. Click the Start bar, and click Control Panels.
2. Double-click Mail.
3. Click Show Profiles.
4. Select the appropriate Outlook profile, and then click Properties.
5. Click E-mail Accounts, and then click Next.
6. Select Microsoft Exchange Server, and then click Change.
7. Click More Settings.
8. Click the Advanced tab.
9. Under Logon network security select None, click OK, and then click
Next. The next time the Outlook client is started there will be a
prompt to enter credentials.