How Can I Get Rid Of My Password Box In Outlook Express?

When you connect to the internet through your internet service provider, the retrieval of messages from POP3 server is hampered. Even though you have saved the password, the password is not retained. Hence, this kind of behavior does not allow you to access your messages. This happens when the windows registry key is altered. Different windows operating systems have different procedure to resolve this issue.

The following information to resolve this kind of problem should only be used when other methods to troubleshoot fail. Before you access the registry to troubleshoot, make sure you have taken a backup of the registry. After you have completed the above step, the next thing is getting rid of account information from the registry. Restart the computer after you have modified the registry. The next step is  to open the outlook express and re-enter the password. This should fix the problem.

The following link would provide very valuable information to troubleshoot this issue
support.microsoft.com/kb/290684.