ngds/common/helpers/Email.php

<?php

namespace common\helpers;

use Yii;

class Email
{
    /**
     * @param string $email
     * @param string $userName
     * @param string $password
     * @return bool
     */
    public static function sendRegistrationEmail(string $email, string $userName, string $password): bool
    {
        $subject = 'Elken Welcome You.';
        $message = \Yii::t('app', 'welcomeEmail', ['userName' => $userName, 'passWord' => $password]);

        $mailer = Yii::$app->mailer;
        $mailer->useFileTransport = false;
        $mailer->compose()
        ->setFrom(trim(Yii::$app->params['adminEmail'], "\r\n"))
        ->setTo(trim($email, "\r\n"))
        ->setSubject($subject)
        ->setHtmlBody($message)
        ->send();

        return true;
    }
}