They had a female mascot in the adverts, and the same actress did the voice announcements for things like "You have Email" , "Welcome to AOL". The US one had a male voice (not sure if they had a mascot) , and there is a contraction in their "You've got mail" announcement.
EDIT : She's called Connie and was mugged http://news.bbc.co.uk/2/hi/uk_news/england/1975629.stm
EDIT2 : OHHH SHIT You helped me find it! I needed the mascot's name!
https://www.zedge.net/notification-sounds/05940a6c-2bce-4791-bf76-ce60f9c2a89b