diff --git a/lib/methods/clusterzonechecktask.cpp b/lib/methods/clusterzonechecktask.cpp
index fd52534c308..404f50dafe1 100644
--- a/lib/methods/clusterzonechecktask.cpp
+++ b/lib/methods/clusterzonechecktask.cpp
@@ -133,6 +133,7 @@ void ClusterZoneCheckTask::ScriptFunc(const Checkable::Ptr& checkable, const Che
 
 	double lastMessageSent = 0;
 	double lastMessageReceived = 0;
+	uint_fast64_t pendingOutgoingMessages = 0;
 	double messagesSentPerSecond = 0;
 	double messagesReceivedPerSecond = 0;
 	double bytesSentPerSecond = 0;
@@ -156,6 +157,7 @@ void ClusterZoneCheckTask::ScriptFunc(const Checkable::Ptr& checkable, const Che
 			if (endpoint->GetLastMessageReceived() > lastMessageReceived)
 				lastMessageReceived = endpoint->GetLastMessageReceived();
 
+			pendingOutgoingMessages += endpoint->GetPendingOutgoingMessages();
 			messagesSentPerSecond += endpoint->GetMessagesSentPerSecond();
 			messagesReceivedPerSecond += endpoint->GetMessagesReceivedPerSecond();
 			bytesSentPerSecond += endpoint->GetBytesSentPerSecond();
@@ -207,6 +209,7 @@ void ClusterZoneCheckTask::ScriptFunc(const Checkable::Ptr& checkable, const Che
 			new PerfdataValue("slave_lag", zoneLag, false, "s", lagWarning, lagCritical),
 			new PerfdataValue("last_messages_sent", lastMessageSent),
 			new PerfdataValue("last_messages_received", lastMessageReceived),
+			new PerfdataValue("sum_pending_outgoing_messages", pendingOutgoingMessages),
 			new PerfdataValue("sum_messages_sent_per_second", messagesSentPerSecond),
 			new PerfdataValue("sum_messages_received_per_second", messagesReceivedPerSecond),
 			new PerfdataValue("sum_bytes_sent_per_second", bytesSentPerSecond),
diff --git a/lib/methods/icingachecktask.cpp b/lib/methods/icingachecktask.cpp
index d3eae1f33f2..5e66fdd3107 100644
--- a/lib/methods/icingachecktask.cpp
+++ b/lib/methods/icingachecktask.cpp
@@ -123,6 +123,7 @@ void IcingaCheckTask::ScriptFunc(const Checkable::Ptr& checkable, const CheckRes
 
 	double lastMessageSent = 0;
 	double lastMessageReceived = 0;
+	uint_fast64_t pendingOutgoingMessages = 0;
 	double messagesSentPerSecond = 0;
 	double messagesReceivedPerSecond = 0;
 	double bytesSentPerSecond = 0;
@@ -136,6 +137,7 @@ void IcingaCheckTask::ScriptFunc(const Checkable::Ptr& checkable, const CheckRes
 		if (endpoint->GetLastMessageReceived() > lastMessageReceived)
 			lastMessageReceived = endpoint->GetLastMessageReceived();
 
+		pendingOutgoingMessages += endpoint->GetPendingOutgoingMessages();
 		messagesSentPerSecond += endpoint->GetMessagesSentPerSecond();
 		messagesReceivedPerSecond += endpoint->GetMessagesReceivedPerSecond();
 		bytesSentPerSecond += endpoint->GetBytesSentPerSecond();
@@ -144,6 +146,7 @@ void IcingaCheckTask::ScriptFunc(const Checkable::Ptr& checkable, const CheckRes
 
 	perfdata->Add(new PerfdataValue("last_messages_sent", lastMessageSent));
 	perfdata->Add(new PerfdataValue("last_messages_received", lastMessageReceived));
+	perfdata->Add(new PerfdataValue("sum_pending_outgoing_messages", pendingOutgoingMessages));
 	perfdata->Add(new PerfdataValue("sum_messages_sent_per_second", messagesSentPerSecond));
 	perfdata->Add(new PerfdataValue("sum_messages_received_per_second", messagesReceivedPerSecond));
 	perfdata->Add(new PerfdataValue("sum_bytes_sent_per_second", bytesSentPerSecond));
diff --git a/lib/remote/endpoint.cpp b/lib/remote/endpoint.cpp
index e534fc17840..fe6e099577b 100644
--- a/lib/remote/endpoint.cpp
+++ b/lib/remote/endpoint.cpp
@@ -101,6 +101,18 @@ Endpoint::Ptr Endpoint::GetLocalEndpoint()
 	return listener->GetLocalEndpoint();
 }
 
+uint_fast64_t Endpoint::GetPendingOutgoingMessages() const
+{
+	uint_fast64_t pending = 0;
+	std::unique_lock lock (m_ClientsLock);
+
+	for (auto& client : m_Clients) {
+		pending += client->GetPendingOutgoingMessages();
+	}
+
+	return pending;
+}
+
 void Endpoint::AddMessageSent(int bytes)
 {
 	double time = Utility::GetTime();
diff --git a/lib/remote/endpoint.hpp b/lib/remote/endpoint.hpp
index d641c2c6b8f..942ea42898e 100644
--- a/lib/remote/endpoint.hpp
+++ b/lib/remote/endpoint.hpp
@@ -39,6 +39,7 @@ class Endpoint final : public ObjectImpl<Endpoint>
 	static Endpoint::Ptr GetLocalEndpoint();
 
 	void SetCachedZone(const intrusive_ptr<Zone>& zone);
+	uint_fast64_t GetPendingOutgoingMessages() const override;
 
 	void AddMessageSent(int bytes);
 	void AddMessageReceived(int bytes);
diff --git a/lib/remote/endpoint.ti b/lib/remote/endpoint.ti
index 78551ecf0dd..1a7c19dee02 100644
--- a/lib/remote/endpoint.ti
+++ b/lib/remote/endpoint.ti
@@ -39,6 +39,10 @@ class Endpoint : ConfigObject
 	Timestamp last_message_sent;
 	Timestamp last_message_received;
 
+	[no_user_modify, no_storage] uint_fast64_t pending_outgoing_messages {
+		get;
+	};
+
 	[no_user_modify, no_storage] double messages_sent_per_second {
 		get;
 	};