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->compose();
        $mailer->setFrom(trim(Yii::$app->params['adminEmail'], "\r\n"));
        $mailer->setTo(trim($email, "\r\n"));
        $mailer->setSubject($subject);
        $mailer->setHtmlBody($message);
        if ($mailer->send()) {
            return true;
        }

        return false;
    }
}