Outlook 2010+
1. Click on File in the Ribbon interface.
2. Click on Options in the sidebar.
3. When the Options screen opens, make sure you are on the Advanced tab by clicking on it.
4. Under the Send and Receive category (you may need to scroll down), click on the Send/Receive... button.
5. Make sure Schedule an automatic send/received every _____ minutes is checked in the window that appears, then adjust the minutes by typing a number into the box next to "minutes" or by clicking on the up or down arrow in that same box.
6. Click Close to close the send/receive options window, then click OK to close the Outlook Options window.
Outlook will now automatically attempt to send or receive mail as often as you have specified.
