I'm in total agreement with Cruise Fanatic on this one. Never open unsolicited email. Just opening it sends a notice to the sender that the email has been opened. This is the surest way to be bombarded with spam. If they identify that the email address is active you'll get plenty more offers. Everything from free cruises to free money from a bank account in Nigeria from someone in the royal family wanting you to accept thier money, just provide your bank account info. If you respond to these type of scams, you'll at some point be asked for bank or credit card info, you know, to set up your onboard account of course. Once they have your info, look out. You're in for an empty account and a lifetime of problems. Delete, delete, delete. If it comes by snail mail throw it away or burn it. Don't apply for a free gym membership or big screen TV to be given away at your local restaurant. Please protect your information, your identity and forget about free things in life. They simply come at too high a price.
One more that is rampant. If you get an email from your bank, don't open it. Your bank does not contact you by email for updates on your account info. It may have a link to a website that looks just like your banks actual website. They mirror the site they are posing as, they look the same, have the same links in the same places, etc. This type of scam has bitten many thousands of people. If in doubt, before you open it, call your bank and ask if they sent you the email. Don't open it!