I want to enter a password in outlook express in order to avoid unauthorised access to it. In case a password for my email is not added still other people can see my previous messages. It only prevents the download of new emails.
Is there any way to required a passord in Outlook Express in order to prohibit someone from seeing any of my emails?

It sounds like you are letting other people use your PC under your log in, if I remember correctly (haven't used Express for years) it set's up accounts for each log in and you can't get access to any other account unless you are an administrator.

So you set up a guest account (for example) which will in turn have it's own Outlook Express profile.