Sometimes when you use Microsoft Office Outlook 2007 or 2003 to open your POP3 mail account (POP3: A common protocol that is used to accept e-mail messages from an Internet e-mail server.) e-mail account, you might be prompted to enter a password even if you specified that your password and it should be saved in your password list. The window looks like this one:
Why is it happening?
There are at least two possible reasons:
You entered your password incorrectly or your Internet service provider (ISP) changed your password.
Your password is correct, but the registry contains incorrect information entered before for the Protected Storage System Provider subkey for your user account.
Reason 1 Microsoft Office Outlook needs to be updated with your new correct 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.
Note that if it is not specified by the ISP, all server and username entries are typed in lowercase letters. Some ISPs require a combination of lowercase and uppercase letters for passwords to get more secure dealing with user accounts. Check with your ISP to figure out if they require a case-sensitive password.
Reason 2 The Microsoft Knowledge Base article 290684 can 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.