Outlook 2013 users can configure email accounts from other service providers such Yahoo, Gmail etc.. And they had already configured those accounts and want Outlook to prompt for username and password before sending or receiving emails then they can follow the below mentioned settings (this example for a Gmail account).
Step 1: Click File menu, navigate to Account Information section under Info menu.
Step 2: Click Account Settings option under Account Information screen and select Account Settings from the drop down.
Step 3: Now in Account Settings screen, select the email account and click change button (you can also double click on the selected email account).
Step 4: Make sure to unmark the check box with caption as “Remember password” under Change Account screen.
Step 5: Clicking Next button will prompt you to enter the password for the selected POP or IMAP account. Enter the required password to confirm and Test Account Settings. Now before sending or receiving emails, Outlook will prompt you to enter the username and password for POP/IMAP account.