How do you look up a united kingdom email adress from the United States?

I'm a soldier from the U.S Army, and last month I met 4 really cool British soldiers at Camp Buerhing Kuwait while we were all waiting to go to Iraq. They gave me their email addresses, all yahoo, but I lost them. I'd like to get back in touch with them, how do I look up a UK email from Yahoo U.S?? Every time I try, it only gives me American Listings. HELP!!