If you are jealous of the privacy of your emails, and you don't want anyone but you to access the contents of your Outlook Express, then what you need is a tool like Outlook Express Privacy.
The mission of Outlook Express Privacy is to allow you control and access to Outlook Express, as well as all email messages. However, once you enable protection, access to any message, not even the address book, is completely unfeasible, unless you enter the password you previously set.
In this way, with Outlook Express Privacy you will maintain the confidentiality of all those emails, and, in addition, you will avoid stealing them.
You can free download Outlook Express Privacy 32, 64 bit and safe install the latest trial or new full version for Windows 10 from the official site.