How To Check Valid Email Is Correct In A Html Form With Php

hello, how can i check to see if a someone puts a valid email in my contact form

lately i have been getting spams and i was wondering if you know how i can verify that the email it was submited is correct? i really need to find out how to check because all these invalid emails i am getting on my contact from in my html i have php and i see that you have many tutorials on php. i also have a wallpaper site and thats where my contact us form is located but lately i just been getting fake email address from the contact html form.

thanks

function CheckEmail($email)
{
  // checks proper E-mail syntax
  if(preg_match( "/^([a-zA-Z0-9])+([a-zA-Z0-9\._-])*@([a-zA-Z0-9_-])+([a-zA-Z0-9\._-]+)+$/", $email)) {
    return true;
  }else{
	  return false;
  }
}