You must ask yourself and answer a few questions in order to determine if the website you're visiting is a legitimate business and not just a website collecting information for future spam emails or telemarketing calls.
Check to see whose running the site. Go to whois.com and look them up. What is their benefit from giving you the information you think you need? Or are they just trying to sell you a product or lure you in for future sales. Nine times out of ten if their offer seems to good to be true, then it probably is. Yes, you've heard that a thousand times, but it is still true.
Fancy Graphics Don't Mean Safety
Don't assume that because the website displays fancy graphics and colorful pages that they are legitimate. Being able to pay for or create elaborate graphics does not mean they are honest. Many of the best websites may be simply black and white print with very few graphics.
Be careful of the information you put into a website, even if you feel ninety per cent sure it's okay. Many times your email or phone number is automatically captured and added to to their database. You may then begin receiving telemarketing calls and spam emails. Any information you put in a website is recorded, somewhere.
Real Time Proof
On one occassion several years ago one of the top credit card companies spelled my name incorrectly and I was unable to get them to fix it. For the last eight years I have received emails and postal mails addressed to that ridiculous name, so they are still profiting from the use of my name. If you're still uneasy about a website or anything a website is offering you, click out of it.
This will also happen if you open a spam email that looks very legitimate or seems to be from a familiar name. You will then be bombarded with spam mail in your inbox. Occassionally you may see emails , where the sender has used your email address in the from field. This is so that you cannot reply and if you try to report the email as spam - you will be reporting yourself.
Always mark spam email as spam so the email program learns to recognize which emails are acceptable.
You can never be too careful. Follow your gut instincts, your instincts will not lead you in a wrong direction.