Mine

<?php

class LoginFormUserValidator extends sfValidatorBase
{
  
  public function configure($options = array(), $messages = array())
  {
    $this->addOption('username_field', 'email');
    $this->addOption('password_field', 'password');

    $this->addMessage('empty', 'Email is mandatory');
    $this->addMessage('notfound', 'This email is not registered');
    $this->addMessage('deleted', 'Your account is deleted');
    $this->addMessage('wrongpass', 'Password is incorrect');
    $this->addMessage('confirmemail', 'Your email needs to be confirmed');
    
  }

  protected function doClean($values)
  {
    $username = isset($values[$this->getOption('username_field')]) ? $values[$this->getOption('username_field')] : '';
    $password = isset($values[$this->getOption('password_field')]) ? $values[$this->getOption('password_field')] : '';

    // don't allow to sign in with an empty username
    if($username)
    {
      $user = Doctrine::getTable('User')->findOneBy('email', $username);

      if($user)
      {
        if(!$user->isDeleted())
        {
          if(!$user->hasConfirmedEmail())
          {
            throw new sfValidatorError($this, 'confirmemail');
          }
          else
          {
            if($user->getPassword() == $password)
            {
              return array_merge($values, array('user' => $user));
            }
            else
            {
              throw new sfValidatorError($this, 'wrongpass');
            }
          }
        }
        else
        {
          throw new sfValidatorError($this, 'deleted');
        }
      }
      else
      {
        throw new sfValidatorError($this, 'notfound');
      }
    }
    else
    {
      throw new sfValidatorError($this, 'empty');
    }
  }
}