title: In PHP, approaches to reduce bots submit form and invalid email accounts?
body: <p>I know its kinda common question, but I cant find a best answer (for now)...</p>
  
  <p>What are the best approaches to reduce bots submit form and invalid email accounts in php and html?</p>
  
  <p>Bots - capthca? hidden css? what else?</p>
  
  <p>Invalid Email - This is truely insane job. How can I detect if the user type: user@yahooo.com, then i said the email is invalid? What if he type: user@yaho.com, user@yahoo1.com, etc... is there anyway to check whether the email is valid?</p>