add phpmailer class to CONTENIDO autoloader

includes/config.plugin.php

@@ -8,4 +8,9 @@ $pluginName = basename(dirname(__DIR__, 1));
 $cfg['plugins'][$pluginName] = cRegistry::getBackendPath() . $cfg['path']['plugins'] . "$pluginName/";
 
 plugin_include($pluginName, 'vendor/autoload.php');
-plugin_include($pluginName, 'classes/PHPMailer.php');
+
+$pluginClassesPath = cRegistry::getBackendPath(true) . cRegistry::getConfigValue('path', 'plugins') . "$pluginName/classes" . DIRECTORY_SEPARATOR;
+
+cAutoload::addClassmapConfig([
+    'PHPMailer' => $pluginClassesPath . 'PHPMailer.php'
+]);