Below will show you how you can enable SMTP authentication for Microsoft Outlook 2000 :
Microsoft Outlook 2000
1. Launch Outlook.
2. Under "Tools" select "Services..."
3. Select "Internet Mail (your account name)" and click "Properties" to edit your account.
4. Click the "Servers" tab.
5. Check the "My Server Requires Authentication" check box and the adjacent "Settings" button.
6. Make sure the "Use same settings as my Incoming Mail Server is checked.