There is an option in Outlook Express to save addresses that you reply to:-
Tools\Options\Send\Automatically put people I reply to in my Address Book
It may be the case you've replied to someone and their address has been added.
HP Envy x2 review: Hands-on
Iconic New York graphic designer Milton Glaser on his uplifting new subway posters
New iMac Pro release date, UK price & specs rumours
Comment suivre le parcours du père Noël ?