Assume it is a scam.
Sounds like the old Irish lottery/sweepstakes scam - where they say you have won a bunch of money, just send a processing fee and they will send it to you - then if you send the "processing fee" they next say you need to pay more for a money transfer fee, then that you have to pay foreign income taxes on it up front, etc, etc - until they have bled you dry oryou wise up and quit paying.
Or they say send a personal check, they trust you - and then proceed to bleed your account dry for you using the account number info on the check, without the hassle of you sending them money time and time again a bit at a time - isn't that nice of them.
If it was not a lottery or sweepstakes that you know for a fact that you entered (in which case it is also illegal to charge a fee to claim it, BTW, at least in US), then why would you believe someone, especially in a foreign country most likely if you google the firms, is trying to give you money for a ticket you never bought ? Google this type of search phrase to read about complaints about these scams - NPF scam complaints - etc.
Count on it being a scam or identity theft. If you have responded to any of these or sent a check to any, assume your identity has been stolen and your bank account is at risk of being cleaned out and should be closed.
What has probably happened, since you say you are getting a lot of them, is two things:
1) you have not registered your name/address with the marketing do-not-mail list, so they are free to send you any sort of junk mail they want
2) you responded to this type of offer or scam at some point (phone or mail or internet) in the past, or frequented a scam site or a site like an online gambling site that marked you as a sucker, so now your name and address is on a "sucker list" of people who are likely gullible or susceptible to this type scam, and that list of names and addresses is now being sold to other shady operators so you will soon be swamped with such "offers" or "winnings".