Commerce account pane email change
I have resolved the issue like adding a submit handler function when click on continue button click. Code is provided below

your-module_form_alter(&amp;$form, $form_state, $form_id) {
   global $user;
   if(!$user-&gt;name){
      $form['account']['login']['mail']['#required'] = 0;
      $form['account']['login']['mail']['#prefix'] = '&lt;div style="display: none;"&gt;';
      $form['account']['login']['mail']['#suffix'] = '&lt;/div&gt;';
      array_unshift($form['buttons']['continue']['#validate'], 'your-module_submit_handler');
    }
}

your-module_submit_handler(&amp;$form, &amp;$form_state){
    $form_state['values']['account']['login']['mail'] = $form['customer_profile_shipping']['field_email']['und'][0]['value']['#value'];
}