title: Swift_TransportException error while signup in yii2 advance template
body: <p>i am using yii2 advanced template and facing problem while sign up in sending email.
  i have used mailtrap to send email and included all details in common/config/mainlocal-php.
  Using Xampp As host.</p>
  
  <p>maillocal.php looks like:</p>
  
  <pre><code>&lt;?php
  return [
      'components' =&gt; [
          'db' =&gt; [
              'class' =&gt; 'yii\db\Connection',
              'dsn' =&gt; 'mysql:host=localhost;dbname=advanced_yii2',
              'username' =&gt; 'root',
              'password' =&gt; '',
              'charset' =&gt; 'utf8',
          ],
          'mail' =&gt; [
          'class' =&gt; 'yii\swiftmailer\Mailer',
                  'viewPath' =&gt; '@common/mail',
                  'useFileTransport' =&gt; false,
                  'transport' =&gt; [
                      'class' =&gt; 'Swift_SmtpTransport',
                      'host' =&gt; 'smtp.mailtrap.io',
                      'username' =&gt; '9**************e',
                      'password' =&gt; '7***************5',
                      'port' =&gt; '2525',
                      'encryption' =&gt; 'tls',
              ],
      ],
      ],
  ];
  
  This is the error i am getting.
  
  Swift_TransportException
  Process could not be started [The system cannot find the path specified.
  ]
  1. in C:\xampp\htdocs\yii-application\vendor\swiftmailer\swiftmailer\lib\classes\Swift\Transport\StreamBuffer.php at line 299
  2. in C:\xampp\htdocs\yii-application\vendor\swiftmailer\swiftmailer\lib\classes\Swift\Transport\StreamBuffer.php at line 54 – Swift_Transport_StreamBuffer::establishProcessConnection()
  3. in C:\xampp\htdocs\yii-application\vendor\swiftmailer\swiftmailer\lib\classes\Swift\Transport\AbstractSmtpTransport.php at line 143 – Swift_Transport_StreamBuffer::initialize(['timeout' =&gt; 30, 'blocking' =&gt; 1, 'command' =&gt; '/usr/sbin/sendmail -bs', 'type' =&gt; 16])
  4. in C:\xampp\htdocs\yii-application\vendor\swiftmailer\swiftmailer\lib\classes\Swift\Transport\SendmailTransport.php at line 50 – Swift_Transport_AbstractSmtpTransport::start()
  5. in C:\xampp\htdocs\yii-application\vendor\yiisoft\yii2-swiftmailer\src\Mailer.php at line 113 – Swift_Transport_SendmailTransport::start()
  6. in C:\xampp\htdocs\yii-application\vendor\yiisoft\yii2-swiftmailer\src\Mailer.php at line 156 – yii\swiftmailer\Mailer::getSwiftMailer()
  7. in C:\xampp\htdocs\yii-application\vendor\yiisoft\yii2\mail\BaseMailer.php at line 263 – yii\swiftmailer\Mailer::sendMessage(yii\swiftmailer\Message)
  8. in C:\xampp\htdocs\yii-application\vendor\yiisoft\yii2\mail\BaseMessage.php at line 49 – yii\mail\BaseMailer::send(yii\swiftmailer\Message)
  9. in C:\xampp\htdocs\yii-application\frontend\models\SignupForm.php at line 77 – yii\mail\BaseMessage::send()
  10. in C:\xampp\htdocs\yii-application\frontend\models\SignupForm.php at line 57 – frontend\models\SignupForm::sendEmail(common\models\User)
  11. in C:\xampp\htdocs\yii-application\frontend\controllers\SiteController.php at line 156 – frontend\models\SignupForm::signup()
  12. frontend\controllers\SiteController::actionSignup()
  13. in C:\xampp\htdocs\yii-application\vendor\yiisoft\yii2\base\InlineAction.php at line 57 – call_user_func_array([frontend\controllers\SiteController, 'actionSignup'], [])
  14. in C:\xampp\htdocs\yii-application\vendor\yiisoft\yii2\base\Controller.php at line 157 – yii\base\InlineAction::runWithParams(['r' =&gt; 'site/signup'])
  15. in C:\xampp\htdocs\yii-application\vendor\yiisoft\yii2\base\Module.php at line 528 – yii\base\Controller::runAction('signup', ['r' =&gt; 'site/signup'])
  16. in C:\xampp\htdocs\yii-application\vendor\yiisoft\yii2\web\Application.php at line 103 – yii\base\Module::runAction('site/signup', ['r' =&gt; 'site/signup'])
  17. in C:\xampp\htdocs\yii-application\vendor\yiisoft\yii2\base\Application.php at line 386 – yii\web\Application::handleRequest(yii\web\Request)
  18. in C:\xampp\htdocs\yii-application\frontend\web\index.php at line 17 – yii\base\Application::run()
  </code></pre>