include.php

См. документацию.

<?
##############################################
# Bitrix: SiteManager                        #
# Copyright (c) 2002-2010 Bitrix             #
# https://www.bitrixsoft.com                 #
# mailto:sources@bitrixsoft.com              #
##############################################
 
require_once($_SERVER["DOCUMENT_ROOT"]."/bitrix/modules/mail/constants.php");
 
\Bitrix\Main\Loader::registerAutoloadClasses(
    'mail',
    array(
        'CMail'                => 'classes/general/mail.php',
        'CMailError'           => 'classes/general/mail.php',
        'CMailHeader'          => 'classes/general/mail.php',
        'CMailAttachment'      => 'classes/general/mail.php',
        'CMailFilter'          => 'classes/general/mail.php',
        'CMailFilterCondition' => 'classes/general/mail.php',
        'CMailLog'             => 'classes/general/mail.php',
 
        'CMailbox'             => 'classes/mysql/mail.php',
        'CMailUtil'            => 'classes/mysql/mail.php',
        'CMailMessage'         => 'classes/mysql/mail.php',
 
        'CSMTPServer'          => 'classes/general/smtp.php',
        'CSMTPServerHost'      => 'classes/general/smtp.php',
        'CSMTPConnection'      => 'classes/general/smtp.php',
 
        'CMailImap'            => 'classes/general/imap.php',
 
        'CMailRestService'     => 'classes/general/rest.php',
 
        'CMailDomain'          => 'classes/general/domain.php',
        'CMailYandex'          => 'classes/general/yandex.php',
        'CMailDomain2'         => 'classes/general/domain2.php',
        'CMailYandex2'         => 'classes/general/yandex2.php',
 
        'CMailDomainRegistrar' => 'classes/general/domain_registrar.php',
        'CMailRegru'           => 'classes/general/regru.php',
 
        'Bitrix\Mail\BaseException'     => 'lib/exception.php',
        'Bitrix\Mail\ReceiverException' => 'lib/exception.php',
    )
);