This is taken from the national-lottery website:
As a general rule, if you have not purchased a ticket for the UK National Lottery, you won’t have won a prize, and you should treat the email with absolute caution.
The following points are some things to look for in order to identify a fraudulent email:
If the email says ‘Winning Notification’ or ‘Lottery Sweep Stake’ in the text, the email you’ve received is not from UK National Lottery;
We don’t tell players how much they've won in an email; and
We don’t ask for any Player information like name, address or bank details on an email.
There is no need to contact us if you have received a lottery related scam (fraudulent) email.
As we are constantly looking to improve our communication with our players, we have now changed all our email addresses to the following:
We will now use only these addresses to send you all important communication such as purchase confirmations.
There is also a good "Common Lottery Scams" link on here: