diff --git a/lib/classes/component.php b/lib/classes/component.php
index 754e44a86c1..5ea3dfd4996 100644
--- a/lib/classes/component.php
+++ b/lib/classes/component.php
@@ -910,18 +910,24 @@ $cache = '.var_export($cache, true).';
      * e.g. get_component_classes_in_namespace('mod_forum', 'event')
      *
      * @param string $component A valid moodle component (frankenstyle)
-     * @param string $namespace Namespace from the component name.
+     * @param string $namespace Namespace from the component name or empty if all $component namespace classes.
      * @return array The full class name as key and the class path as value.
      */
     public static function get_component_classes_in_namespace($component, $namespace = '') {
 
-        // We will add them later.
-        $namespace = ltrim($namespace, '\\');
+        $component = self::normalize_componentname($component);
 
-        // We need add double backslashes as it is how classes are stored into self::$classmap.
-        $namespace = implode('\\\\', explode('\\', $namespace));
+        if ($namespace) {
 
-        $regex = '/^' . $component . '\\\\' . $namespace . '/';
+            // We will add them later.
+            $namespace = trim($namespace, '\\');
+
+            // We need add double backslashes as it is how classes are stored into self::$classmap.
+            $namespace = implode('\\\\', explode('\\', $namespace));
+            $namespace = $namespace . '\\\\';
+        }
+
+        $regex = '|^' . $component . '\\\\' . $namespace . '|';
         $it = new RegexIterator(new ArrayIterator(self::$classmap), $regex, RegexIterator::GET_MATCH, RegexIterator::USE_KEY);
 
         // We want to be sure that they exist.
diff --git a/lib/tests/component_test.php b/lib/tests/component_test.php
index b3294117219..0fac4c2ceba 100644
--- a/lib/tests/component_test.php
+++ b/lib/tests/component_test.php
@@ -458,15 +458,33 @@ class core_component_testcase extends advanced_testcase {
         $this->assertCount(0, core_component::get_component_classes_in_namespace('core_unexistingcomponent', 'something'));
         $this->assertCount(0, core_component::get_component_classes_in_namespace('auth_cas', 'something'));
 
+        // Matches the last namespace level name not partials.
+        $this->assertCount(0, core_component::get_component_classes_in_namespace('auth_cas', 'tas'));
+        $this->assertCount(0, core_component::get_component_classes_in_namespace('core_user', 'course'));
+        $this->assertCount(0, core_component::get_component_classes_in_namespace('mod_forum', 'output\\emaildigest'));
+        $this->assertCount(0, core_component::get_component_classes_in_namespace('mod_forum', '\\output\\emaildigest'));
+        $this->assertCount(2, core_component::get_component_classes_in_namespace('mod_forum', 'output\\email'));
+        $this->assertCount(2, core_component::get_component_classes_in_namespace('mod_forum', '\\output\\email'));
+        $this->assertCount(2, core_component::get_component_classes_in_namespace('mod_forum', 'output\\email\\'));
+        $this->assertCount(2, core_component::get_component_classes_in_namespace('mod_forum', '\\output\\email\\'));
+
         // Prefix with backslash if it doesn\'t come prefixed.
         $this->assertCount(1, core_component::get_component_classes_in_namespace('auth_cas', 'task'));
         $this->assertCount(1, core_component::get_component_classes_in_namespace('auth_cas', '\\task'));
 
-        // Core as a component works.
+        // Core as a component works, the funcion can normalise the component name.
         $this->assertCount(7, core_component::get_component_classes_in_namespace('core', 'update'));
+        $this->assertCount(7, core_component::get_component_classes_in_namespace('', 'update'));
+        $this->assertCount(7, core_component::get_component_classes_in_namespace('moodle', 'update'));
 
         // Multiple levels.
         $this->assertCount(5, core_component::get_component_classes_in_namespace('core_user', '\\output\\myprofile\\'));
+        $this->assertCount(5, core_component::get_component_classes_in_namespace('core_user', 'output\\myprofile\\'));
         $this->assertCount(5, core_component::get_component_classes_in_namespace('core_user', '\\output\\myprofile'));
+        $this->assertCount(5, core_component::get_component_classes_in_namespace('core_user', 'output\\myprofile'));
+
+        // Without namespace it returns classes/ classes.
+        $this->assertCount(2, core_component::get_component_classes_in_namespace('tool_mobile', ''));
+        $this->assertCount(1, core_component::get_component_classes_in_namespace('tool_filetypes'));
     }
 }
diff --git a/mod/forum/classes/output/email/renderer.php b/mod/forum/classes/output/email/renderer.php
index 10a19e42f15..17657fde33f 100644
--- a/mod/forum/classes/output/email/renderer.php
+++ b/mod/forum/classes/output/email/renderer.php
@@ -26,6 +26,8 @@ namespace mod_forum\output\email;
 
 defined('MOODLE_INTERNAL') || die();
 
+require_once(__DIR__ . '/../../../renderer.php');
+
 /**
  * Forum post renderable.
  *