diff --git a/README.md b/README.md
index f6b72f5..db9d13c 100644
--- a/README.md
+++ b/README.md
@@ -58,3 +58,14 @@ Navodila za konstruiranje fajlov pa so tukaj: https://www.drupal.org/docs/contri
 ### Endpoint za dodajanje pojmov
 
 V modulu [yufu_concept](web/modules/custom/yufu_concept/yufu_concept.info.yml "yufu_concept").
+
+
+### Obveščanje prek mailov
+
+1. Ko je dodan nov pojem ali posodobljen star pojem, obvesti o tem vse urednike.
+- ob novi draft revizija se poslje mail urednikom
+
+2. Ko je sprejet nov pojem ali revizija, obvesti uporabnika in ga odblokiraj.
+- ob novi publishani revizijami se poslje mail uporabniku, ki jo je naredil.
+
+Funkcionalnost se nahaja v yufu_admin modulu.
diff --git a/composer.json b/composer.json
index e980592..003a46b 100644
--- a/composer.json
+++ b/composer.json
@@ -23,6 +23,7 @@
         "drupal/core-composer-scaffold": "^10.0",
         "drupal/core-project-message": "^10.0",
         "drupal/core-recommended": "^10.0",
+        "drupal/diff": "^1.1",
         "drupal/gin": "^3.0@RC",
         "drupal/gin_toolbar": "^1.0@RC",
         "drupal/jsonapi_menu_items": "^1.2",
diff --git a/composer.lock b/composer.lock
index f029d26..7c1d6be 100644
--- a/composer.lock
+++ b/composer.lock
@@ -4,7 +4,7 @@
         "Read more about it at https://getcomposer.org/doc/01-basic-usage.md#installing-dependencies",
         "This file is @generated automatically"
     ],
-    "content-hash": "185dc0d2be2be9514fc2dad73c4205d1",
+    "content-hash": "2ca7e5f483ed127efa757db4cb8d35ca",
     "packages": [
         {
             "name": "asm89/stack-cors",
@@ -62,6 +62,67 @@
             },
             "time": "2022-01-18T09:12:03+00:00"
         },
+        {
+            "name": "caxy/php-htmldiff",
+            "version": "v0.1.15",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/caxy/php-htmldiff.git",
+                "reference": "6342b02ddb86fd36093ad7e2db2efc21f01ab7cd"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/caxy/php-htmldiff/zipball/6342b02ddb86fd36093ad7e2db2efc21f01ab7cd",
+                "reference": "6342b02ddb86fd36093ad7e2db2efc21f01ab7cd",
+                "shasum": ""
+            },
+            "require": {
+                "ext-dom": "*",
+                "ext-mbstring": "*",
+                "ezyang/htmlpurifier": "^4.7",
+                "php": ">=7.3"
+            },
+            "require-dev": {
+                "doctrine/cache": "~1.0",
+                "phpunit/phpunit": "~9.0"
+            },
+            "suggest": {
+                "doctrine/cache": "Used for caching the calculated diffs using a Doctrine Cache Provider"
+            },
+            "type": "library",
+            "extra": {
+                "branch-alias": {
+                    "dev-master": "0.1.x-dev"
+                }
+            },
+            "autoload": {
+                "psr-0": {
+                    "Caxy\\HtmlDiff": "lib/"
+                }
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "GPL-2.0"
+            ],
+            "authors": [
+                {
+                    "name": "Josh Schroeder",
+                    "email": "jschroeder@caxy.com",
+                    "homepage": "http://www.caxy.com"
+                }
+            ],
+            "description": "A library for comparing two HTML files/snippets and highlighting the differences using simple HTML.",
+            "homepage": "https://github.com/caxy/php-htmldiff",
+            "keywords": [
+                "diff",
+                "html"
+            ],
+            "support": {
+                "issues": "https://github.com/caxy/php-htmldiff/issues",
+                "source": "https://github.com/caxy/php-htmldiff/tree/v0.1.15"
+            },
+            "time": "2023-11-05T23:49:04+00:00"
+        },
         {
             "name": "chi-teck/drupal-code-generator",
             "version": "2.6.2",
@@ -1718,6 +1779,97 @@
             },
             "time": "2023-12-06T09:22:56+00:00"
         },
+        {
+            "name": "drupal/diff",
+            "version": "1.1.0",
+            "source": {
+                "type": "git",
+                "url": "https://git.drupalcode.org/project/diff.git",
+                "reference": "8.x-1.1"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://ftp.drupal.org/files/projects/diff-8.x-1.1.zip",
+                "reference": "8.x-1.1",
+                "shasum": "b7558b0f431d5945289829946e0beba61bf7ae18"
+            },
+            "require": {
+                "drupal/core": "^9.3 || ^10",
+                "mkalkbrenner/php-htmldiff-advanced": "~0.0.8"
+            },
+            "type": "drupal-module",
+            "extra": {
+                "drupal": {
+                    "version": "8.x-1.1",
+                    "datestamp": "1665437355",
+                    "security-coverage": {
+                        "status": "covered",
+                        "message": "Covered by Drupal's security advisory policy"
+                    }
+                }
+            },
+            "notification-url": "https://packages.drupal.org/8/downloads",
+            "license": [
+                "GPL-2.0-or-later"
+            ],
+            "authors": [
+                {
+                    "name": "Miro Dietiker (miro_dietiker)",
+                    "homepage": "https://www.drupal.org/u/miro_dietiker",
+                    "role": "Maintainer"
+                },
+                {
+                    "name": "Juampy NR (juampynr)",
+                    "homepage": "https://www.drupal.org/u/juampynr",
+                    "role": "Maintainer"
+                },
+                {
+                    "name": "Lucian Hangea (lhangea)",
+                    "homepage": "https://www.drupal.org/u/lhangea",
+                    "role": "Maintainer"
+                },
+                {
+                    "name": "Alan D.",
+                    "homepage": "https://www.drupal.org/u/alan-d.",
+                    "role": "Maintainer"
+                },
+                {
+                    "name": "Brian Gilbert (realityloop).",
+                    "homepage": "https://www.drupal.org/u/realityloop",
+                    "role": "Maintainer"
+                },
+                {
+                    "name": "lhangea",
+                    "homepage": "https://www.drupal.org/user/2743803"
+                },
+                {
+                    "name": "miro_dietiker",
+                    "homepage": "https://www.drupal.org/user/227761"
+                },
+                {
+                    "name": "phenaproxima",
+                    "homepage": "https://www.drupal.org/user/205645"
+                },
+                {
+                    "name": "realityloop",
+                    "homepage": "https://www.drupal.org/user/139189"
+                },
+                {
+                    "name": "rötzi",
+                    "homepage": "https://www.drupal.org/user/73064"
+                },
+                {
+                    "name": "yhahn",
+                    "homepage": "https://www.drupal.org/user/264833"
+                }
+            ],
+            "description": "Compares two entity revisions",
+            "homepage": "https://www.drupal.org/project/diff",
+            "support": {
+                "source": "http://cgit.drupalcode.org/diff",
+                "issues": "https://www.drupal.org/project/issues/diff"
+            }
+        },
         {
             "name": "drupal/gin",
             "version": "3.0.0-rc7",
@@ -2476,6 +2628,67 @@
             },
             "time": "2023-11-17T07:53:29+00:00"
         },
+        {
+            "name": "ezyang/htmlpurifier",
+            "version": "v4.17.0",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/ezyang/htmlpurifier.git",
+                "reference": "bbc513d79acf6691fa9cf10f192c90dd2957f18c"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/ezyang/htmlpurifier/zipball/bbc513d79acf6691fa9cf10f192c90dd2957f18c",
+                "reference": "bbc513d79acf6691fa9cf10f192c90dd2957f18c",
+                "shasum": ""
+            },
+            "require": {
+                "php": "~5.6.0 || ~7.0.0 || ~7.1.0 || ~7.2.0 || ~7.3.0 || ~7.4.0 || ~8.0.0 || ~8.1.0 || ~8.2.0 || ~8.3.0"
+            },
+            "require-dev": {
+                "cerdic/css-tidy": "^1.7 || ^2.0",
+                "simpletest/simpletest": "dev-master"
+            },
+            "suggest": {
+                "cerdic/css-tidy": "If you want to use the filter 'Filter.ExtractStyleBlocks'.",
+                "ext-bcmath": "Used for unit conversion and imagecrash protection",
+                "ext-iconv": "Converts text to and from non-UTF-8 encodings",
+                "ext-tidy": "Used for pretty-printing HTML"
+            },
+            "type": "library",
+            "autoload": {
+                "files": [
+                    "library/HTMLPurifier.composer.php"
+                ],
+                "psr-0": {
+                    "HTMLPurifier": "library/"
+                },
+                "exclude-from-classmap": [
+                    "/library/HTMLPurifier/Language/"
+                ]
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "LGPL-2.1-or-later"
+            ],
+            "authors": [
+                {
+                    "name": "Edward Z. Yang",
+                    "email": "admin@htmlpurifier.org",
+                    "homepage": "http://ezyang.com"
+                }
+            ],
+            "description": "Standards compliant HTML filter written in PHP",
+            "homepage": "http://htmlpurifier.org/",
+            "keywords": [
+                "html"
+            ],
+            "support": {
+                "issues": "https://github.com/ezyang/htmlpurifier/issues",
+                "source": "https://github.com/ezyang/htmlpurifier/tree/v4.17.0"
+            },
+            "time": "2023-11-17T15:01:25+00:00"
+        },
         {
             "name": "grasmash/expander",
             "version": "3.0.0",
@@ -3051,6 +3264,47 @@
             },
             "time": "2023-08-12T08:29:29+00:00"
         },
+        {
+            "name": "mkalkbrenner/php-htmldiff-advanced",
+            "version": "0.0.8",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/mkalkbrenner/php-htmldiff.git",
+                "reference": "3a714b48c9c3d3730baaf6d3949691e654cd37c9"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/mkalkbrenner/php-htmldiff/zipball/3a714b48c9c3d3730baaf6d3949691e654cd37c9",
+                "reference": "3a714b48c9c3d3730baaf6d3949691e654cd37c9",
+                "shasum": ""
+            },
+            "require": {
+                "caxy/php-htmldiff": ">=0.0.6",
+                "php": ">=5.5.0"
+            },
+            "type": "library",
+            "autoload": {
+                "files": [
+                    "src/HtmlDiffAdvancedInterface.php",
+                    "src/HtmlDiffAdvanced.php"
+                ]
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "GNU General Public License V2"
+            ],
+            "description": "An add-on for the php-htmldiff library for comparing two HTML files/snippets and highlighting the differences using simple HTML.",
+            "homepage": "https://github.com/mkalkbrenner/php-htmldiff",
+            "keywords": [
+                "diff",
+                "html"
+            ],
+            "support": {
+                "issues": "https://github.com/mkalkbrenner/php-htmldiff/issues",
+                "source": "https://github.com/mkalkbrenner/php-htmldiff/tree/master"
+            },
+            "time": "2016-07-25T17:07:32+00:00"
+        },
         {
             "name": "nikic/php-parser",
             "version": "v4.17.1",
diff --git a/web/modules/custom/yufu_admin/yufu_admin.module b/web/modules/custom/yufu_admin/yufu_admin.module
index 7dd23f6..7d7b030 100644
--- a/web/modules/custom/yufu_admin/yufu_admin.module
+++ b/web/modules/custom/yufu_admin/yufu_admin.module
@@ -7,6 +7,7 @@
 
 use Drupal\Core\Entity\EntityInterface;
 use Drupal\Core\Url;
+use Drupal\node\NodeInterface;
 
 /**
  * Implements hook_entity_operation().
@@ -28,3 +29,122 @@ function yufu_admin_entity_operation(EntityInterface $entity) {
   }
   return $operations;
 }
+
+/**
+ * Implements hook_mail().
+ */
+function yufu_admin_mail($key, &$message, $params) {
+  $options = ['langcode' => $message['langcode']];
+
+  switch ($key) {
+    case 'concept_drafted':
+      $message['from'] = \Drupal::config('system.site')->get('mail');
+      $message['subject'] = t('YUFU: New concept draft: @title', ['@title' => $params['node_title']], $options);
+      $message['body'][] = $params['message'];
+      break;
+    case 'concept_approved':
+      $message['from'] = \Drupal::config('system.site')->get('mail');
+      $message['subject'] = t('YUFU: Your concept (changes) were approved: @title', ['@title' => $params['node_title']], $options);
+      $message['body'][] = $params['message'];
+      break;
+    case 'concept_rejected':
+      $message['from'] = \Drupal::config('system.site')->get('mail');
+      $message['subject'] = t('YUFU: Your concept (changes) were rejected: @title', ['@title' => $params['node_title']], $options);
+      $message['body'][] = $params['message'];
+  }
+}
+
+/**
+ * Implements hook_ENTITY_TYPE_presave().
+ */
+function yufu_admin_node_presave(EntityInterface $entity) {
+  if ($entity instanceOf NodeInterface && $entity->bundle() == 'concept') {
+    // Get transition: concept_drafted, concept_approved, concept_rejected.
+    if ($entity->isNew()) {
+      $transition = 'concept_drafted';
+    }
+    else {
+      $transition = _yufu_admin_get_node_transition($entity);
+    }
+    switch ($transition) {
+      case 'concept_drafted':
+        // Send email to editors.
+        _yufu_admin_concept_drafted_mail($entity);
+        break;
+      case 'concept_approved':
+        // Send email to revision creator (user).
+        break;
+      case 'concept_rejectd':
+        // Send email to revision creator (user).
+        // This transition happens on revision delete.
+        // Curently it is dead.
+        break;
+    }
+  }
+}
+
+/**
+ * Compare original node moderation state with current state.
+ *
+ * @param \Drupal\node\NodeInterface $node
+ *   Node to check transition on.
+ *
+ * @return string|null
+ *   Name of the transition.
+ */
+function _yufu_admin_get_node_transition(NodeInterface $node) {
+  $original = $node->original;
+  $moderation_state = $node->moderation_state->value;
+  $previous_state = $original->moderation_state->value;
+  if ($moderation_state == 'draft' && $previous_state == 'published') {
+    return 'concept_drafted';
+  }
+  else if ($moderation_state == 'published' && $previous_state == 'draft') {
+    return 'concept_approved';
+  }
+  else if ($moderation_state == 'published' && $previous_state == 'published') {
+    return 'stay_published';
+  }
+  else if ($moderation_state == 'draft' && $previous_state == 'draft') {
+    return 'stay_draft';
+  }
+  return NULL;
+}
+
+function _yufu_admin_concept_drafted_mail(NodeInterface $node) {
+  $mailManager = \Drupal::service('plugin.manager.mail');
+  $module = 'yufu_admin';
+  $key = 'concept_drafted';
+  // To all editors.
+  $to = _yufu_admin_get_all_editors_emails();
+  $params['message'] = t('New concept created: @title - @url', [
+    'title' => $node->getTitle(),
+    'url' => $node->toUrl()->toString(),
+  ]);
+  $params['node_title'] = $entity->label();
+  $langcode = \Drupal::currentUser()->getPreferredLangcode();
+  $send = true;
+
+  $result = $mailManager->mail($module, $key, $to, $langcode, $params, NULL, $send);
+  if ($result['result'] !== true) {
+    drupal_set_message(t('There was a problem sending your message and it was not sent.'), 'error');
+  }
+  else {
+    drupal_set_message(t('Your message has been sent.'));
+  }
+}
+
+function _yufu_admin_get_all_editors_emails() {
+  $user_storage = \Drupal::entityTypeManager()->getStorage('user');
+  $ids = $user_storage->getQuery()
+    ->condition('status', 1)
+    ->condition('roles', 'administrator')
+    ->execute();
+  $editors = $user_storage->loadMultiple($ids);
+  $emails = [];
+  foreach ($editors as $editor) {
+    /* @var \Drupal\user\UserInterface $user */
+    $emails[] = $editor->getEmail();
+  }
+  return $emails;
+}