[FrameworkBundle] Ensure Email class exists before using it

Author: Kocal

DependencyInjection/Configuration.php

@@ -1067,7 +1067,7 @@ private function addValidationSection(ArrayNodeDefinition $rootNode, callable $e
                             ->validate()->castToArray()->end()
                         ->end()
                         ->scalarNode('translation_domain')->defaultValue('validators')->end()
-                        ->enumNode('email_validation_mode')->values(Email::VALIDATION_MODES + ['loose'])->end()
+                        ->enumNode('email_validation_mode')->values((class_exists(Email::class) ? Email::VALIDATION_MODES : ['html5-allow-no-tld', 'html5', 'strict']) + ['loose'])->end()
                         ->arrayNode('mapping')
                             ->addDefaultsIfNotSet()
                             ->fixXmlConfig('path')