I am a Website designer, and I can tell you that you got an "autoresponder" -- the equivalent of a form letter. Autoresponders are just as the name implies: Prewritten emails that go out automatically ...
Intrigued by the post on the News section of this site, I did some digging. You can find the rules for the promotion here: http://www.mcdonalds.co.uk/giveaway/asp/GA_tc.asp