Latest: I've had multiple independent reports that suggest the scammers are starting to use snail mail (Post Office mail) to target potential victims in a very similar manner to their lottery e-mail scams. The same advice applies - bin any letters you receive, ignore them and do not reply to them.
Firstly, the scammer has to construct a reasonably convincing-sounding "you've won the lottery" e-mail, so they're now tending to throw in verifiable correct facts in there to make it sound legitimate. The three most common things they put in are:
Of course, they then blow this to smithereens by using a free Webmail-based e-mail account (e.g. yahoo.co.uk, hotmail.com and so on) to send their scam e-mail from - do you really think Camelot (who run the UK lottery) would ever send e-mail to end-users from a Yahoo! Mail or Hotmail account? Nope, they never would and this should be enough to stop you dead in your tracks and delete the scam e-mail.
It should be noted here that the only legal place to buy UK lottery tickets (and, yes, you have to buy them - there is no such thing as a "free UK lottery sweepstake" in existence) on the Internet is at the official UK lottery site located at http://www.national-lottery.co.uk/ and even then you need a UK address and a UK debit card. Any other site that says it sells UK lottery tickets is breaking the law. If you have not bought your ticket from either an official UK lottery physical terminal (e.g. in a UK newsagent, UK supermarket etc.) or from the official site mentioned above, then you *cannot* win a UK lottery prize.
Note that even Camelot themselves have now stopped e-mailing people who won via an online ticket (and not a moment too soon - you now have to log into the official Web site to discover you've won, which is as it should be). Hence, any person/organisation sending you e-mail saying you've won a (usually large) prize on the UK lottery is lying, it's as simple as that.
The first e-mail you will receive will usually avoid mentioning any "processing/claim/courier fee" that you'll have pay to them - this is to try to hook you in to the scam and not scare you off right away. Instead, the scammer will ask for as much personal information as possible (full name, address, date of birth etc.) - this is useful for them if you get so deep into the scam that they might want to try forging documents with your info on them. Don't give them any info (you deleted that e-mail anyway didn't you ?).
The scammer will often say "don't tell anyone about this win" (by "anyone", they probably mean the police, so that they won't be tracked down and prosecuted !), which is a very silly instruction for them give if you think about it. Who are they to say who you can and can't tell that you've "won" the lottery ?
If you are foolish enough to have started up a phone or e-mail conversation with the scammers, they will inevitably try to get a "claim fee" from you to process the lottery win. Let me see - you've "won" a lottery you never entered in the first place and now you're expected to pay possibly thousands of pounds to someone you've never heard of to get hold of "winnings" that they provide no proof whatsoever even exists ?! If you haven't twigged it's a scam at this point, you're quite a naive person to say the least.
Sadly, if you have fallen for the scam and actually sent them money, then you probably have no chance of recovering the money you sent, especially if it's to a different country (that fact that someone outside the UK would be involved in a UK lottery really should have set alarm bells ringing). If it's within your own country, perhaps contacting the police might be a start or possibly the standards trading officers for the county involved, but I don't hold out much hope of ever getting your money back.
Some more reading on this subject to further enlighten you:
The official Camelot site's
Months after I put this page up warning about scams, Camelot finally did something similar. Because of their tardiness (especially poor since scam e-mails often mention the official site and Camelot's postal address!), I've been fielding way too many "I'd like to claim my prize" e-mails, which hopefully will now go to the official site Webmaster and not me (update: nope, still getting a stream of queries about scam e-mails, ho hum).
The UK Government's
list of scam types
Basically says the same thing as this page (don't communicate with them and delete any messages from them).
How not to win a million
Interesting article, including some bloke from the Midlands who was conned out of almost 20,000 Euros.
The Dutch Lottery Scam
This page is handy because it gives you some useful advice on how to report advance fee frauds.
A shockingly high number of lottery fraudsters out there!
Please note - although scammers have used my name in their fraudulent e-mails, I am NOT involved in any way with any of these scams. Having read this page, I hope you realise that I don't need to be e-mailed about these scams - if they use my name and claim you've won the lottery, they are fraudulent and should be ignored. I did get one very funny UK lottery scam e-mail though which I think is worth sharing with you , but sadly, it was the exception to the rule.