Ошибка 500 после регистрации closed

Swift_TransportExceptionPOST /admin/admin_mass_email.php
Expected response code 250 but got code "553", with message "553 5.7.1 Sender address rejected: not owned by auth user.
 "

Swift_TransportExceptionPOST /admin/admin_mass_email.php
Expected response code 250 but got code "553", with message "553 5.7.1 Sender address rejected: not owned by auth user.
 "

Ваши логи (которые есть и у вас же в папке с ними). Собственно что можно сказать по ним - в настройках smtp вы указали некую почту vasya@yandex.ru, а сами пытаетесь слать с blabla@bla.ru. Вывод - надо в конфиге указать этот же ящик как адрес форума.

// Email
$bb_cfg['emailer'] = [
    'enabled' => true,
    'smtp' => [
        'enabled' => true, // send email via external SMTP server
        'host' => 'smtp.yandex.ru', // SMTP server host
        'port' => 465, // SMTP server port
        'username' => 'torrent@assasinfil.ru', // SMTP username (if server requires it)
        'password' => '----', // SMTP password (if server requires it)
    ],
    'ssl_type' => 'ssl', // SMTP ssl type (ssl or tls)
];

$bb_cfg['board_email'] = "torrent@assasinfil.ru"; // admin email address
$bb_cfg['board_email_form'] = false; // can users send email to each other via board
$bb_cfg['board_email_sig'] = ''; // this text will be attached to all emails the board sends
$bb_cfg['board_email_sitename'] = $domain_name; // sitename used in all emails header

$bb_cfg['topic_notify_enabled'] = true;
$bb_cfg['pm_notify_enabled'] = true;
$bb_cfg['group_send_email'] = true;
$bb_cfg['email_change_disabled'] = false; // disable changing email by user

$bb_cfg['bounce_email'] = "torrent@assasinfil.ru"; // bounce email address
$bb_cfg['tech_admin_email'] = "torrent@assasinfil.ru"; // email for sending error reports
$bb_cfg['abuse_email'] = "torrent@assasinfil.ru";
$bb_cfg['adv_email'] = "torrent@assasinfil.ru";