Searching contacts

When I create an email, click 'To' and search for a company saved in my address book, even though I'm searching on 'all columns', no contact appears. I can't always remember a specific persons name or email address but I do know the company name. If I search the company name in the actual contacts section of Outlook, they do appear so why not when searching in the 'To' box? The company name is in the 'company' field in the saved contact.