diff --git a/src/Model/Item.php b/src/Model/Item.php
index 89b81b99a..887072eb8 100644
--- a/src/Model/Item.php
+++ b/src/Model/Item.php
@@ -672,7 +672,8 @@ class Item
 
 		$fields['parent-item'] = ['guid' => 'parent-guid', 'network' => 'parent-network'];
 
-		$fields['parent-item-author'] = ['url' => 'parent-author-link', 'name' => 'parent-author-name'];
+		$fields['parent-item-author'] = ['url' => 'parent-author-link', 'name' => 'parent-author-name',
+			'network' => 'parent-author-network'];
 
 		$fields['event'] = ['created' => 'event-created', 'edited' => 'event-edited',
 			'start' => 'event-start','finish' => 'event-finish',
diff --git a/src/Protocol/Diaspora.php b/src/Protocol/Diaspora.php
index 7f4690879..0115814bd 100644
--- a/src/Protocol/Diaspora.php
+++ b/src/Protocol/Diaspora.php
@@ -2332,13 +2332,24 @@ class Diaspora
 		Logger::info('Participation stored', ['id' => $message_id, 'guid' => $guid, 'parent_guid' => $parent_guid, 'author' => $author]);
 
 		// Send all existing comments and likes to the requesting server
-		$comments = Item::select(['id', 'uri-id', 'parent', 'verb'], ['parent' => $parent_item['id'], 'gravity' => [GRAVITY_COMMENT, GRAVITY_ACTIVITY]]);
+		$comments = Item::select(['id', 'uri-id', 'parent-author-network', 'author-network', 'verb'],
+			['parent' => $parent_item['id'], 'gravity' => [GRAVITY_COMMENT, GRAVITY_ACTIVITY]]);
 		while ($comment = Item::fetch($comments)) {
-			if (in_array($comment["verb"], [Activity::FOLLOW, Activity::TAG])) {
+			if (in_array($comment['verb'], [Activity::FOLLOW, Activity::TAG])) {
 				Logger::info('participation messages are not relayed', ['item' => $comment['id']]);
 				continue;
 			}
 
+			if ($comment['author-network'] == Protocol::ACTIVITYPUB) {
+				Logger::info('Comments from ActivityPub authors are not relayed', ['item' => $comment['id']]);
+				continue;
+			}
+
+			if ($comment['parent-author-network'] == Protocol::ACTIVITYPUB) {
+				Logger::info('Comments to comments from ActivityPub authors are not relayed', ['item' => $comment['id']]);
+				continue;
+			}
+
 			Logger::info('Deliver participation', ['item' => $comment['id'], 'contact' => $author_contact["cid"]]);
 			if (Worker::add(PRIORITY_HIGH, 'Delivery', Delivery::POST, $comment['id'], $author_contact["cid"])) {
 				Post\DeliveryData::incrementQueueCount($comment['uri-id'], 1);
diff --git a/src/Worker/Notifier.php b/src/Worker/Notifier.php
index 07bb99df2..892015252 100644
--- a/src/Worker/Notifier.php
+++ b/src/Worker/Notifier.php
@@ -461,17 +461,17 @@ class Notifier
 					}
 
 					if (!empty($rr['addr']) && ($rr['network'] == Protocol::ACTIVITYPUB) && !DBA::exists('fcontact', ['addr' => $rr['addr']])) {
-						Logger::info('Contact is AP omly', ['target' => $target_id, 'contact' => $rr['url']]);
+						Logger::info('Contact is AP omly, so skip delivery via legacy DFRN/Diaspora', ['target' => $target_id, 'contact' => $rr['url']]);
 						continue;
 					}
 
 					if (!empty($rr['id']) && Contact::isArchived($rr['id'])) {
-						Logger::info('Contact is archived', ['target' => $target_id, 'contact' => $rr['url']]);
+						Logger::info('Contact is archived, so skip delivery', ['target' => $target_id, 'contact' => $rr['url']]);
 						continue;
 					}
 
 					if (self::isRemovalActivity($cmd, $owner, $rr['network'])) {
-						Logger::log('Skipping dropping for ' . $rr['url'] . ' since the network supports account removal commands.', Logger::DEBUG);
+						Logger::info('Contact does no supports account removal commands, so skip delivery', ['target' => $target_id, 'contact' => $rr['url']]);
 						continue;
 					}
 
@@ -480,6 +480,11 @@ class Notifier
 						continue;
 					}
 
+					if (self::skipActivityPubForDiaspora($rr, $target_item, $thr_parent)) {
+						Logger::info('Contact is from Diaspora, but the replied author is from ActivityPub, so skip delivery via Diaspora', ['id' => $target_id, 'url' => $rr['url']]);
+						continue;
+					}
+
 					$conversants[] = $rr['id'];
 
 					Logger::info('Public delivery', ['target' => $target_id, 'guid' => $target_item["guid"], 'to' => $rr]);
@@ -511,17 +516,17 @@ class Notifier
 			}
 
 			if (!empty($contact['addr']) && ($contact['network'] == Protocol::ACTIVITYPUB) && !DBA::exists('fcontact', ['addr' => $contact['addr']])) {
-				Logger::info('Contact is AP omly', ['target' => $target_id, 'contact' => $contact['url']]);
+				Logger::info('Contact is AP omly, so skip delivery via legacy DFRN/Diaspora', ['target' => $target_id, 'contact' => $contact['url']]);
 				continue;
 			}
 
 			if (!empty($contact['id']) && Contact::isArchived($contact['id'])) {
-				Logger::info('Contact is archived', ['target' => $target_id, 'contact' => $contact['url']]);
+				Logger::info('Contact is archived, so skip delivery', ['target' => $target_id, 'contact' => $contact['url']]);
 				continue;
 			}
 
 			if (self::isRemovalActivity($cmd, $owner, $contact['network'])) {
-				Logger::log('Skipping dropping for ' . $contact['url'] . ' since the network supports account removal commands.', Logger::DEBUG);
+				Logger::info('Contact does no supports account removal commands, so skip delivery', ['target' => $target_id, 'contact' => $contact['url']]);
 				continue;
 			}
 
@@ -530,6 +535,11 @@ class Notifier
 				continue;
 			}
 
+			if (self::skipActivityPubForDiaspora($contact, $target_item, $thr_parent)) {
+				Logger::info('Contact is from Diaspora, but the replied author is from ActivityPub, so skip delivery via Diaspora', ['id' => $target_id, 'url' => $rr['url']]);
+				continue;
+			}
+
 			// Don't deliver to Diaspora if it already had been done as batch delivery
 			if (($contact['network'] == Protocol::DIASPORA) && $batch_delivery) {
 				Logger::log('Already delivered  id ' . $target_id . ' via batch to ' . json_encode($contact), Logger::DEBUG);
@@ -602,6 +612,35 @@ class Notifier
 		return;
 	}
 
+	/**
+	 * Checks if the current delivery shouldn't be transported to Diaspora.
+	 * This is done for posts from AP authors or posts that are comments to AP authors.
+	 *
+	 * @param array  $contact    Receiver of the post
+	 * @param array  $item       The post
+	 * @param array  $thr_parent The thread parent
+	 * @return bool
+	 */
+	private static function skipActivityPubForDiaspora(array $contact, array $item, array $thr_parent)
+	{
+		// No skipping needs to be done when delivery isn't done to Diaspora
+		if ($contact['network'] != Protocol::DIASPORA) {
+			return false;
+		}
+
+		// Skip the delivery to Diaspora if the item is from an ActivityPub author
+		if ($item['author-network'] == Protocol::ACTIVITYPUB) {
+			return true;
+		}
+		
+		// Skip the delivery to Diaspora if the thread parent is from an ActivityPub author
+		if ($thr_parent['author-network'] == Protocol::ACTIVITYPUB) {
+			return true;
+		}
+
+		return false;
+	}
+
 	/**
 	 * Checks if the current delivery process needs to be transported via DFRN.
 	 *