After registration, store email address and redirect to to another page
In your submit handler, you could use drupal_set_message to set the message like this:

function custom_user_register_submit($form, &amp;$form_state) {
  $form_state['redirect'] = 'content/welcome';
  drupal_set_message('Your mail is @mail', array('@mail' =&gt; $form_state['user']-&gt;mail));
}


You could also save it in the $_SESSION if you don't want to use drupal_set_message and get it from there.