Note: August 17, 2016: If you're connected to an Exchange 2013 server, you might be prompted to enter your user name and password in Outlook, even though you're logged in to your computer with your network credentials and Outlook should silently log you in. We apologize for any inconvenience this issue has caused and want to let you know that we're actively working to resolve this issue. We will update this page when we release a fix.
Each time you use Microsoft Office Outlook 2007 to connect to your POP3 e-mail account, you might be prompted for a password even if you specified that your password should be saved in your password list.
There are at least two possible causes:
Cause 1 You entered your password incorrectly or your Internet service provider (ISP) changed your password.
Cause 2 You saved your password but the registry contains incorrect information for the Protected Storage System Provider subkey for the user account.
Cause 1 Microsoft Outlook needs to be updated with your new password. Microsoft cannot retrieve your old password. Contact your ISP, and ask them to assign a new password to your account. After you get your new password, you must update your e-mail account settings. See Change your ISP e-mail account information for instructions.
Note: Unless specified by your ISP, all server and address entries are typed in lowercase letters. Some ISPs require a combination of lowercase and uppercase letters for passwords, to add further security. Check with your ISP to see if they require a case-sensitive password.
Cause 2 The Microsoft Knowledge Base article 290684 is available to help you correct this behavior by stepping you through the process of removing your user account information from the Protected Storage System Provider subkey in the Windows Registry and entering your password options again in Outlook.