diff --git a/src/Protocol/ActivityPub/Processor.php b/src/Protocol/ActivityPub/Processor.php
index e7073ab878..dee70f152c 100644
--- a/src/Protocol/ActivityPub/Processor.php
+++ b/src/Protocol/ActivityPub/Processor.php
@@ -16,6 +16,7 @@ use Friendica\Content\Text\HTML;
 use Friendica\Util\JsonLD;
 use Friendica\Core\Config;
 use Friendica\Protocol\ActivityPub;
+use Friendica\Util\DateTimeFormat;
 
 /**
  * ActivityPub Processor Protocol class
@@ -101,6 +102,24 @@ class Processor
 		return $item;
 	}
 
+	/**
+	 * Updates a message
+	 *
+	 * @param array  $activity Activity array
+	 */
+	public static function updateItem($activity)
+	{
+		$item = [];
+		$item['changed'] = DateTimeFormat::utcNow();
+		$item['edited'] = $activity['updated'];
+		$item['title'] = HTML::toBBCode($activity['name']);
+		$item['content-warning'] = HTML::toBBCode($activity['summary']);
+		$item['body'] = self::convertMentions(HTML::toBBCode($activity['content']));
+		$item['tag'] = self::constructTagList($activity['tags'], $activity['sensitive']);
+
+		Item::update($item, ['uri' => $activity['id']]);
+	}
+
 	/**
 	 * Prepares data for a message
 	 *
@@ -128,22 +147,6 @@ class Processor
 		self::postItem($activity, $item);
 	}
 
-	/**
-	 * Prepare the item array for a "like"
-	 *
-	 * @param array  $activity Activity array
-	 */
-	public static function likeItem($activity)
-	{
-		$item = [];
-		$item['verb'] = ACTIVITY_LIKE;
-		$item['parent-uri'] = $activity['object_id'];
-		$item['gravity'] = GRAVITY_ACTIVITY;
-		$item['object-type'] = ACTIVITY_OBJ_NOTE;
-
-		self::postItem($activity, $item);
-	}
-
 	/**
 	 * Delete items
 	 *
@@ -158,14 +161,15 @@ class Processor
 	}
 
 	/**
-	 * Prepare the item array for a "dislike"
+	 * Prepare the item array for an activity
 	 *
 	 * @param array  $activity Activity array
+	 * @param string $verb     Activity verb
 	 */
-	public static function dislikeItem($activity)
+	public static function createActivity($activity, $verb)
 	{
 		$item = [];
-		$item['verb'] = ACTIVITY_DISLIKE;
+		$item['verb'] = $verb;
 		$item['parent-uri'] = $activity['object_id'];
 		$item['gravity'] = GRAVITY_ACTIVITY;
 		$item['object-type'] = ACTIVITY_OBJ_NOTE;
@@ -176,7 +180,8 @@ class Processor
 	/**
 	 * Create an event
 	 *
-	 * @param array  $activity Activity array
+	 * @param array $activity Activity array
+	 * @param array $item
 	 */
 	public static function createEvent($activity, $item)
 	{
diff --git a/src/Protocol/ActivityPub/Receiver.php b/src/Protocol/ActivityPub/Receiver.php
index f7c041a8ae..e94940a39e 100644
--- a/src/Protocol/ActivityPub/Receiver.php
+++ b/src/Protocol/ActivityPub/Receiver.php
@@ -21,14 +21,7 @@ use Friendica\Util\DateTimeFormat;
  * @brief ActivityPub Receiver Protocol class
  *
  * To-Do:
- * - Update (Image, Video, Article, Note)
  * - Undo Announce
- * - Accept Event
- * - Reject Event
- * - TentativeAccept Even
- * - Undo Accept Event
- * - Undo Reject Event
- * - Undo TentativeAccept Event
  *
  * Check what this is meant to do:
  * - Add
@@ -36,7 +29,6 @@ use Friendica\Util\DateTimeFormat;
  * - Flag
  * - Remove
  * - Undo Block
- * - Undo Accept Person
  */
 class Receiver
 {
@@ -125,10 +117,11 @@ class Receiver
 	 */
 	private static function fetchObjectType($activity, $object_id)
 	{
-
-		$object_type = JsonLD::fetchElement($activity['as:object'], '@type');
-		if (!empty($object_type)) {
-			return $object_type;
+		if (!empty($activity['as:object'])) {
+			$object_type = JsonLD::fetchElement($activity['as:object'], '@type');
+			if (!empty($object_type)) {
+				return $object_type;
+			}
 		}
 
 		if (Item::exists(['uri' => $object_id, 'gravity' => [GRAVITY_PARENT, GRAVITY_COMMENT]])) {
@@ -193,7 +186,7 @@ class Receiver
 		$object_type = self::fetchObjectType($activity, $object_id);
 
 		// Fetch the content only on activities where this matters
-		if (in_array($type, ['as:Create', 'as:Announce'])) {
+		if (in_array($type, ['as:Create', 'as:Update', 'as:Announce'])) {
 			if ($type == 'as:Announce') {
 				$trust_source = false;
 			}
@@ -219,6 +212,11 @@ class Receiver
 			$object_data['object_actor'] = JsonLD::fetchElement($activity['as:object'], 'as:actor');
 			$object_data['object_object'] = JsonLD::fetchElement($activity['as:object'], 'as:object');
 			$object_data['object_type'] = JsonLD::fetchElement($activity['as:object'], '@type');
+
+			// An Undo is done on the object of an object, so we need that type as well
+			if ($type == 'as:Undo') {
+				$object_data['object_object_type'] = self::fetchObjectType([], $object_data['object_object']);
+			}
 		}
 
 		$object_data = self::addActivityFields($object_data, $activity);
@@ -311,20 +309,32 @@ class Receiver
 		switch ($type) {
 			case 'as:Create':
 			case 'as:Announce':
-				ActivityPub\Processor::createItem($object_data);
+				if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
+					ActivityPub\Processor::createItem($object_data);
+				}
 				break;
 
 			case 'as:Like':
-				ActivityPub\Processor::likeItem($object_data);
+				if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
+					ActivityPub\Processor::createActivity($object_data, ACTIVITY_LIKE);
+				}
 				break;
 
 			case 'as:Dislike':
-				ActivityPub\Processor::dislikeItem($object_data);
+				if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
+					ActivityPub\Processor::createActivity($object_data, ACTIVITY_DISLIKE);
+				}
+				break;
+
+			case 'as:TentativeAccept':
+				if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
+					ActivityPub\Processor::createActivity($object_data, ACTIVITY_ATTENDMAYBE);
+				}
 				break;
 
 			case 'as:Update':
 				if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
-					/// @todo
+					ActivityPub\Processor::updateItem($object_data);
 				} elseif (in_array($object_data['object_type'], self::ACCOUNT_TYPES)) {
 					ActivityPub\Processor::updatePerson($object_data, $body);
 				}
@@ -339,31 +349,42 @@ class Receiver
 				break;
 
 			case 'as:Follow':
-				ActivityPub\Processor::followUser($object_data);
+				if (in_array($object_data['object_type'], self::ACCOUNT_TYPES)) {
+					ActivityPub\Processor::followUser($object_data);
+				}
 				break;
 
 			case 'as:Accept':
 				if ($object_data['object_type'] == 'as:Follow') {
 					ActivityPub\Processor::acceptFollowUser($object_data);
+				} elseif (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
+					ActivityPub\Processor::createActivity($object_data, ACTIVITY_ATTEND);
 				}
 				break;
 
 			case 'as:Reject':
 				if ($object_data['object_type'] == 'as:Follow') {
 					ActivityPub\Processor::rejectFollowUser($object_data);
+				} elseif (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
+					ActivityPub\Processor::createActivity($object_data, ACTIVITY_ATTENDNO);
 				}
 				break;
 
 			case 'as:Undo':
-				if ($object_data['object_type'] == 'as:Follow') {
+				if (($object_data['object_type'] == 'as:Follow') &&
+					in_array($object_data['object_object_type'], self::ACCOUNT_TYPES)) {
 					ActivityPub\Processor::undoFollowUser($object_data);
-				} elseif (in_array($object_data['object_type'], self::ACTIVITY_TYPES)) {
+				} elseif (($object_data['object_type'] == 'as:Accept') &&
+					in_array($object_data['object_object_type'], self::ACCOUNT_TYPES)) {
+					ActivityPub\Processor::rejectFollowUser($object_data);
+				} elseif (in_array($object_data['object_type'], self::ACTIVITY_TYPES) &&
+					in_array($object_data['object_object_type'], self::CONTENT_TYPES)) {
 					ActivityPub\Processor::undoActivity($object_data);
 				}
 				break;
 
 			default:
-				logger('Unknown activity: ' . $type, LOGGER_DEBUG);
+				logger('Unknown activity: ' . $type . ' ' . $object_data['object_type'], LOGGER_DEBUG);
 				break;
 		}
 	}
diff --git a/src/Protocol/ActivityPub/Transmitter.php b/src/Protocol/ActivityPub/Transmitter.php
index 9f98409c33..bfc26cd9f1 100644
--- a/src/Protocol/ActivityPub/Transmitter.php
+++ b/src/Protocol/ActivityPub/Transmitter.php
@@ -282,8 +282,7 @@ class Transmitter
 			foreach ($activity[$element] as $receiver) {
 				if ($receiver == $profile['followers'] && !empty($item_profile['followers'])) {
 					$permissions[$element][] = $item_profile['followers'];
-				}
-				if (!in_array($receiver, $exclude)) {
+				} elseif (!in_array($receiver, $exclude)) {
 					$permissions[$element][] = $receiver;
 				}
 			}
@@ -309,13 +308,13 @@ class Transmitter
 
 		$data = ['to' => [], 'cc' => [], 'bcc' => []];
 
-		$data = array_merge($data, self::fetchPermissionBlockFromConversation($item));
-
 		$actor_profile = APContact::getByURL($item['author-link']);
 
 		$terms = Term::tagArrayFromItemId($item['id'], TERM_MENTION);
 
 		if (!$item['private']) {
+			$data = array_merge($data, self::fetchPermissionBlockFromConversation($item));
+
 			$data['to'][] = ActivityPub::PUBLIC_COLLECTION;
 			if (!empty($actor_profile['followers'])) {
 				$data['cc'][] = $actor_profile['followers'];