Souke/backend/models/MailForm.php

<?php

namespace backend\models;

use Yii;
use yii\base\Model;

/**
 * ContactForm is the model behind the contact form.
 */
class MailForm extends Model {

    public $subject;
    public $body;

    /**
     * @inheritdoc
     */
    public function rules() {
        return [
            // name, email, subject and body are required
            [['subject', 'body'], 'required', 'message' => 'Champs obligatoire'],
        ];
    }

    /**
     * @inheritdoc
     */
    public function attributeLabels() {
        return [
            'subject' => 'Sujet',
            'body' => 'Message',
        ];
    }

    /**
     * Sends an email to the specified email address using the information collected by this model.
     *
     * @param  string  $email the target email address
     * @return boolean whether the email was sent
     */
    public function sendEmail($email) {

        return Yii::$app->mailer->compose()
            ->setTo($email)
            ->setFrom(['matthieu@lechatdesnoisettes.com' => 'Le Chat des Noisettes'])
            ->setSubject($this->subject)
            ->setTextBody($this->body)
            ->send();
    }

}