How to enable SMTP authentication on Outlook 2007
1. Select the 'Tools' menu and click 'Account settings'
2. Select the account you wish to enable authentication on and click 'Change'
3. Select the 'more settings' button
4. Select the 'Out going Server' tab
5. Place a check in the box labelled 'My outgoing server requires authentication' and the box thats labelled 'Log on to incoming mail server before sending'
6. Click 'OK'
7. Click 'Next'
8. Click 'Finish'