(from the Swisslos page)
FRAUD RISK THROUGH BOGUS LOTTERIES
Several people received emails or letters in the last few weeks which were sent in the name of Swisslos or other originators. The recipients were told that they were the winners of a sizeable amount of money but in order to claim it, they would have to provide their personal information such as their address, financial data and, in certain cases they were even asked to prepay a handling fee. We are quite certain that this constitutes fraud. We urge you not to respond to any such correspondence.
Swisslos never informs its winners in this manner. Please be aware that you can only win if you have actually played the lottery and can provide a valid lottery receipt.