title: Best way for registration which prevents anti automation
body: <p>On my webservice, I have a registration form where the user can register with email address, username and password. For anti-automation, I send a confirmation-link to the email address.</p>
  
  <p>This is how most of the webservices do it.
  But I´m thinking to go away from that email mechanism and simply use a captcha instead to prevent automated registrations.</p>
  
  <p>What are the pros / cons of these two approaches regarding security and usability? And are there other mechanisms for that?</p>