'mailer' => [
'class' => 'yii\swiftmailer\Mailer',
// send all mails to a file by default. You have to set
// 'useFileTransport' to false and configure a transport
// for the mailer to send real emails.
'useFileTransport' => false,
'transport' => [
'class' => 'Swift_SmtpTransport',
'host' => $params['smtp_host'],
'port' => $params['smtp_port'],
'encryption' => $params['smtp_encryption'],
'username' => $params['username'],
'password' => $params['password']
]
],