Created user email might reveal the email address of the user!

Email registration is great module.
The only problem is that the auto created usernames mighr reveal the real email of a user.
For example someone with email JohnDoe@hotmail.com will be the user with the user name JohnDoe . If someone want to find and use -spam email addresses could guess that the user name of the user is the first part of the email address before the @ . Then it is easy to try different major mail services to identify the real email address. So the only think he has to do is to send mail to JohnDoe@gmail.com, JohnDoe@aol.com, JohnDoe@yahoo.com and finally JohnDoe@hotmail.com!!!!

I recomend another way to create the user name from email. My changes to email_registration.module follows .

function email_registration_user($op, &$edit, &$account, $category = NULL) {
  switch ($op) {
    case 'insert':
      // Other modules may implement hook_email_registration_name($edit, $account)
      // to generate a username (return a string to be used as the username, NULL
      // to have email_registration generate it)
      $names = module_invoke_all('email_registration_name', $edit, $account);
      // Remove any empty entries
      $names = array_filter($names);
	
      if (empty($names)) {
        // Default implementation of name generation
        $namenew = preg_replace('/@.*$/', '', $edit['mail']);
//Create a new user name using the email address and a timestamp
+      $namenew = str_pad($namenew, 14, strval(time())); /// be sure that you have at least 10 characters for the new username
+	$left = left($namenew,5);  
+	$right = right($namenew,5);
+	$namenew = $left.$right;  //construct a user name using 5 characters from the begin and 5 characters from the end 

		
		// if username generated from email record already exists, append underscore and number eg:(chris_123)
        if (db_result(db_query("SELECT count(*) FROM {users} WHERE uid <> %d AND LOWER(name) = LOWER('%s')", $account->uid, $namenew)) > 0) {
          // find the next number available to append to the name
          $sql = "SELECT SUBSTRING_INDEX(name,'_',-1) FROM {users} WHERE name REGEXP '%s' ORDER BY CAST(SUBSTRING_INDEX(name,'_',-1) AS UNSIGNED) DESC LIMIT 1";
          $nameidx = db_result(db_query($sql, '^'. $namenew .'_[0-9]+$'));
          $namenew .= '_'. ($nameidx + 1);
        }
      }
      else {
        // One would expect a single implementation of the hook, but if there
        // are multiples out there use the last one
        $namenew = array_pop($names);
      }

      // replace with generated username
      db_query("UPDATE {users} SET name = '%s' WHERE uid = '%s'", $namenew, $account->uid);
      $account->name = $namenew;
      break;
  }
  return;
}

function right($value, $count){
    return substr($value, ($count*-1));
}
 
function left($string, $count){
    return substr($string, 0, $count);
}

I believe that this could help someone