When you are sending e-mail to someone and you can't remember his or her full name or e-mail address, just type as much as you know in the To box—for example, his or her first name. Outlook Express will search your address book to find an entry that matches the incomplete address.
If more than one person in your address book has the same first name, Outlook Express displays all matching names, and you can select the one you want. If it cannot find a match, it then searches any directory services you have set up to to check e-mail names.