Insert/create user in database using login form
It is not possible to create a user account in Drupal without writing an email account.

An example of how you can create a user programmatically is:

 $new_user = array(
  'name' =&gt; 'name',
  'mail' =&gt; 'name@email.com',
  'pass' =&gt; 'password', // note: do not md5 the password
  'status' =&gt; 1
 );

 //custom fields
 $new_user-&gt;field_name_lasname['und'][0]['value'] = 'Name and Last Name';
 //custom fields ( custom fields) 
 $new_user-&gt;field_referenced_field_['und'][0]['target_id'] = 0;

 user_save(null, $new_user);


Please excuse me my English is not good