diff --git a/src/Core/Worker.php b/src/Core/Worker.php
index a06a11043..76400d469 100644
--- a/src/Core/Worker.php
+++ b/src/Core/Worker.php
@@ -243,7 +243,9 @@ class Worker
 			self::execFunction($queue, $include, $argv, true);
 
 			$stamp = (float)microtime(true);
-			if (DBA::update('workerqueue', ['done' => true], ['id' => $queue['id']])) {
+
+			$condition = ["`id` = ? AND `next_try` < ?", $queue['id'], DateTimeFormat::utcNow()];
+			if (DBA::update('workerqueue', ['done' => true], $condition)) {
 				Config::set('system', 'last_worker_execution', DateTimeFormat::utcNow());
 			}
 			self::$db_duration = (microtime(true) - $stamp);
@@ -1137,8 +1139,8 @@ class Worker
 		$id = $queue['id'];
 
 		if ($retrial > 14) {
-			logger('Id ' . $id . ' had been tried 14 times, it will be deleted now.', LOGGER_DEBUG);
-			DBA::delete('workerqueue', ['id' => $id]);
+			logger('Id ' . $id . ' had been tried 14 times. We stop now.', LOGGER_DEBUG);
+			return;
 		}
 
 		// Calculate the delay until the next trial
diff --git a/src/Protocol/ActivityPub/Transmitter.php b/src/Protocol/ActivityPub/Transmitter.php
index a0d92a571..a37d03537 100644
--- a/src/Protocol/ActivityPub/Transmitter.php
+++ b/src/Protocol/ActivityPub/Transmitter.php
@@ -936,6 +936,8 @@ class Transmitter
 	 * @param integer $uid User ID
 	 * @param string $inbox Target inbox
 	 * @param integer $suggestion_id Suggestion ID
+	 *
+	 * @return boolean was the transmission successful?
 	 */
 	public static function sendContactSuggestion($uid, $inbox, $suggestion_id)
 	{
@@ -957,7 +959,7 @@ class Transmitter
 		$signed = LDSignature::sign($data, $owner);
 
 		logger('Deliver profile deletion for user ' . $uid . ' to ' . $inbox . ' via ActivityPub', LOGGER_DEBUG);
-		HTTPSignature::transmit($signed, $inbox, $uid);
+		return HTTPSignature::transmit($signed, $inbox, $uid);
 	}
 
 	/**
@@ -965,6 +967,8 @@ class Transmitter
 	 *
 	 * @param integer $uid User ID
 	 * @param string $inbox Target inbox
+	 *
+	 * @return boolean was the transmission successful?
 	 */
 	public static function sendProfileDeletion($uid, $inbox)
 	{
@@ -984,7 +988,7 @@ class Transmitter
 		$signed = LDSignature::sign($data, $owner);
 
 		logger('Deliver profile deletion for user ' . $uid . ' to ' . $inbox . ' via ActivityPub', LOGGER_DEBUG);
-		HTTPSignature::transmit($signed, $inbox, $uid);
+		return HTTPSignature::transmit($signed, $inbox, $uid);
 	}
 
 	/**
@@ -992,6 +996,8 @@ class Transmitter
 	 *
 	 * @param integer $uid User ID
 	 * @param string $inbox Target inbox
+	 *
+	 * @return boolean was the transmission successful?
 	 */
 	public static function sendProfileUpdate($uid, $inbox)
 	{
@@ -1011,7 +1017,7 @@ class Transmitter
 		$signed = LDSignature::sign($data, $owner);
 
 		logger('Deliver profile update for user ' . $uid . ' to ' . $inbox . ' via ActivityPub', LOGGER_DEBUG);
-		HTTPSignature::transmit($signed, $inbox, $uid);
+		return HTTPSignature::transmit($signed, $inbox, $uid);
 	}
 
 	/**
diff --git a/src/Util/HTTPSignature.php b/src/Util/HTTPSignature.php
index 503cbff0a..1d2e7d9f7 100644
--- a/src/Util/HTTPSignature.php
+++ b/src/Util/HTTPSignature.php
@@ -272,9 +272,11 @@ class HTTPSignature
 	/**
 	 * @brief Transmit given data to a target for a user
 	 *
-	 * @param $data
-	 * @param $target
-	 * @param $uid
+	 * @param array $data Data that is about to be send
+	 * @param string $target The URL of the inbox
+	 * @param integer $uid User id of the sender
+	 *
+	 * @return boolean Was the transmission successful?
 	 */
 	public static function transmit($data, $target, $uid)
 	{
@@ -303,8 +305,11 @@ class HTTPSignature
 		$headers[] = 'Content-Type: application/activity+json';
 
 		$postResult = Network::post($target, $content, $headers);
+		$return_code = $postResult->getReturnCode();
 
-		logger('Transmit to ' . $target . ' returned ' . $postResult->getReturnCode());
+		logger('Transmit to ' . $target . ' returned ' . $return_code);
+
+		return ($return_code >= 200) && ($return_code <= 299);
 	}
 
 	/**
diff --git a/src/Worker/APDelivery.php b/src/Worker/APDelivery.php
index 7b1ad7605..b952249fe 100644
--- a/src/Worker/APDelivery.php
+++ b/src/Worker/APDelivery.php
@@ -7,6 +7,7 @@ namespace Friendica\Worker;
 use Friendica\BaseObject;
 use Friendica\Protocol\ActivityPub;
 use Friendica\Model\Item;
+use Friendica\Core\Worker;
 use Friendica\Util\HTTPSignature;
 
 class APDelivery extends BaseObject
@@ -23,19 +24,25 @@ class APDelivery extends BaseObject
 	{
 		logger('Invoked: ' . $cmd . ': ' . $item_id . ' to ' . $inbox, LOGGER_DEBUG);
 
+		$success = true;
+
 		if ($cmd == Delivery::MAIL) {
 		} elseif ($cmd == Delivery::SUGGESTION) {
-			ActivityPub\Transmitter::sendContactSuggestion($uid, $inbox, $item_id);
+			$success = ActivityPub\Transmitter::sendContactSuggestion($uid, $inbox, $item_id);
 		} elseif ($cmd == Delivery::RELOCATION) {
 		} elseif ($cmd == Delivery::REMOVAL) {
-			ActivityPub\Transmitter::sendProfileDeletion($uid, $inbox);
+			$success = ActivityPub\Transmitter::sendProfileDeletion($uid, $inbox);
 		} elseif ($cmd == Delivery::PROFILEUPDATE) {
-			ActivityPub\Transmitter::sendProfileUpdate($uid, $inbox);
+			$success = ActivityPub\Transmitter::sendProfileUpdate($uid, $inbox);
 		} else {
 			$data = ActivityPub\Transmitter::createCachedActivityFromItem($item_id);
 			if (!empty($data)) {
-				HTTPSignature::transmit($data, $inbox, $uid);
+				$success = HTTPSignature::transmit($data, $inbox, $uid);
 			}
 		}
+
+		if (!$success) {
+			Worker::defer();
+		}
 	}
 }