When you use e-mail, you may become a victim of SPAM (wikipedia).
Recently, spammers don’t only send simple advertisements. Some spammers send a massive amount of spams, such as several hundred per day, to your cell phone. Those spammers’ plot is to make you disgusted at hundres of “You’ve got mail!” on your cell phone, and they try to lead you to their “Unsubscribe Form” on the Website.
Once you access the “Unsubscribe Form”, you may be required to fill out the form with your real name, your phone number, your real address, and so on. If you follow their instruction, your personal information will fall into the wrong hands.
So, if you are receiving SPAMs on your cell phone, NEVER access the Websites written on the SPAM. There are filtering services provided by the phone company, so you should use those services instead of accessing the “Unsubscribe Form”.