Outlook 2003 ships by default to NOT automatically send/receive messages during a specific time interval. To set up an automatic send/receive every 5 minutes, follow these instructions:

1. Click the Tools menu and choose Options....
   
2. Choose the Mail Setup tab from the Options pop-up window.
   
3. Click the Send/Receive button to open the Send/Receive Groups pop-up window..
   
4. Under the Setting for group "All Accounts" section, select the checkbox for "Schedule an automatic send/receive every 5 minutes."
   
5. Click to Close the Send/Receive Groups pop-up window.
   
6. Click OK to close the Options pop-up window and save your change.