Yandex SMTP limit for outgoing emails

After some research, I decided to write a custom transporter class to use multiple email address. Here you can find the codes:

// app\MailQueue.php
<?php

namespace App;

use Illuminate\Support\Facades\Cache;
use Illuminate\Support\Facades\Config;

class MailQueue
{
    protected int $queueMaxSize = 5;
    protected int $mailLimitByUser = 100;

    protected int $queueSize = 0;

    protected int $front = 0;

    protected array $users = [];

    public function __construct()
    {
        if(Cache::missing('MailQueue')) {
            Cache::put('MailQueue', [
                'front' => 0,
                'queueSize' => 0
            ]);
        }

        $this->front = Cache::get('MailQueue')['front'];
        $this->queueSize = Cache::get('MailQueue')['queueSize'];
        $this->users = config('mail.mailers.smtp.users');

        if (count($this->users) < $this->queueMaxSize) {
            $this->queueMaxSize = count($this->users);
        }
    }


    public function advanceQueue(): void
    {
        // select the user according to queueSize
        // 0-99 => 1
        // 100-199 => 2
        // 200-299 => 3
        // 300-399 => 4
        // 400-499 => 5
        $user = $this->users[(int) ceil($this->queueSize / $this->mailLimitByUser) + 1];

        // set the user's credentials
        $this->setUser($user);

        // increase the queueSize
        $this->queueSize++;

        // if the queueSize is greater than the queueMaxSize, reset the queueSize
        if($this->queueSize >= $this->queueMaxSize * $this->mailLimitByUser) {
            $this->queueSize = 0;
        }

        // update the cache
        Cache::put('MailQueue', [
            'front' => $this->front,
            'queueSize' => $this->queueSize
        ]);
    }

    private function setUser(array $user): void
    {
        Config::set('mail.mailers.smtp.username', $user['username']);
        Config::set('mail.from.address', $user['username']);

        Config::set('mail.mailers.smtp.password', $user['password']);
    }

}

// app\Transports\MultiSmtpTransport.php
<?php

namespace App\Transports;

use App\MailQueue;
use Symfony\Component\Mailer\Transport\Smtp\SmtpTransport;
class MultiSmtpTransport extends SmtpTransport
{
    public function __construct(MailQueue $mailQueue)
    {
        parent::__construct();
        $mailQueue->advanceQueue();
    }

    public function __toString(): string
    {
        return 'multi_smtp';
    }
}

// config/mail.php
        'smtp' => [
            'transport' => 'multi_smtp',
            'host' => env('MAIL_HOST', 'smtp.mailgun.org'),
            'port' => /*****/,
            'users' => [
                1 => [
                    'username' => env('MAIL_USERNAME1'),
                    'password' => env('MAIL_PASSWORD1'),
                ],
                2 => [
                    'username' => env('MAIL_USERNAME2'),
                    'password' => env('MAIL_PASSWORD2'),
                ],
                3 => [
                    'username' => env('MAIL_USERNAME3'),
                    'password' => env('MAIL_PASSWORD3'),
                ]
            ]/*...*/
        ],

// and finally do not forget to extend the `multi_smtp` transporter. In serviceProvider:
        Mail::extend('multi_smtp', function (array $config = []) {
            return new MultiSmtpTransport(new MailQueue());
        });