diff --git a/lib/methods/clusterzonechecktask.cpp b/lib/methods/clusterzonechecktask.cpp
index 07a03a97a..f98fa7723 100644
--- a/lib/methods/clusterzonechecktask.cpp
+++ b/lib/methods/clusterzonechecktask.cpp
@@ -134,6 +134,7 @@ 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;
@@ -157,6 +158,7 @@ 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();
@@ -208,6 +210,7 @@ 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 aa2061ef0..81541d684 100644
--- a/lib/methods/icingachecktask.cpp
+++ b/lib/methods/icingachecktask.cpp
@@ -124,6 +124,7 @@ 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;
@@ -137,6 +138,7 @@ 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();
@@ -145,6 +147,7 @@ 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 d558347b7..5a4fa76c8 100644
--- a/lib/remote/endpoint.cpp
+++ b/lib/remote/endpoint.cpp
@@ -110,6 +110,18 @@ 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 dcf5b0f19..28fe7ae84 100644
--- a/lib/remote/endpoint.hpp
+++ b/lib/remote/endpoint.hpp
@@ -46,6 +46,7 @@ public:
 	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 019dda89d..864080e8c 100644
--- a/lib/remote/endpoint.ti
+++ b/lib/remote/endpoint.ti
@@ -40,6 +40,10 @@ 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;
 	};
diff --git a/lib/remote/jsonrpcconnection.cpp b/lib/remote/jsonrpcconnection.cpp
index 0d40de1de..df26f6076 100644
--- a/lib/remote/jsonrpcconnection.cpp
+++ b/lib/remote/jsonrpcconnection.cpp
@@ -158,6 +158,7 @@ void JsonRpcConnection::WriteOutgoingMessages(boost::asio::yield_context yc)
 					}
 
 					size_t bytesSent = JsonRpc::SendRawMessage(m_Stream, message, yc);
+					m_PendingOutgoingMessages.fetch_sub(1, std::memory_order_relaxed);
 
 					if (m_Endpoint) {
 						m_Endpoint->AddMessageSent(bytesSent);
@@ -234,6 +235,7 @@ void JsonRpcConnection::SendRawMessage(const String& message)
 
 		m_OutgoingMessagesQueue.emplace_back(message);
 		m_OutgoingMessagesQueued.Set();
+		m_PendingOutgoingMessages.fetch_add(1, std::memory_order_relaxed);
 	});
 }
 
@@ -245,6 +247,7 @@ void JsonRpcConnection::SendMessageInternal(const Dictionary::Ptr& message)
 
 	m_OutgoingMessagesQueue.emplace_back(JsonEncode(message));
 	m_OutgoingMessagesQueued.Set();
+	m_PendingOutgoingMessages.fetch_add(1, std::memory_order_relaxed);
 }
 
 void JsonRpcConnection::Disconnect()
diff --git a/lib/remote/jsonrpcconnection.hpp b/lib/remote/jsonrpcconnection.hpp
index 78b64322b..d13803d27 100644
--- a/lib/remote/jsonrpcconnection.hpp
+++ b/lib/remote/jsonrpcconnection.hpp
@@ -57,6 +57,11 @@ public:
 	Shared<AsioTlsStream>::Ptr GetStream() const;
 	ConnectionRole GetRole() const;
 
+	auto GetPendingOutgoingMessages() const noexcept
+	{
+		return m_PendingOutgoingMessages.load(std::memory_order_relaxed);
+	}
+
 	void Disconnect();
 
 	void SendMessage(const Dictionary::Ptr& request);
@@ -79,6 +84,7 @@ private:
 	boost::asio::io_context::strand m_IoStrand;
 	std::vector<String> m_OutgoingMessagesQueue;
 	AsioEvent m_OutgoingMessagesQueued;
+	Atomic<decltype(m_OutgoingMessagesQueue)::size_type> m_PendingOutgoingMessages {0};
 	AsioEvent m_WriterDone;
 	Atomic<bool> m_ShuttingDown;
 	WaitGroup::Ptr m_WaitGroup;