diff --git a/cmd/waku/rest/relay.go b/cmd/waku/rest/relay.go
index 4cce1daa9..484fef0b2 100644
--- a/cmd/waku/rest/relay.go
+++ b/cmd/waku/rest/relay.go
@@ -3,6 +3,7 @@ package rest
 import (
 	"context"
 	"encoding/json"
+	"errors"
 	"net/http"
 	"strings"
 	"sync"
@@ -15,9 +16,10 @@ import (
 	"go.uber.org/zap"
 )
 
-const ROUTE_RELAY_SUBSCRIPTIONSV1 = "/relay/v1/subscriptions"
-const ROUTE_RELAY_MESSAGESV1 = "/relay/v1/messages/{topic}"
+const routeRelayV1Subscriptions = "/relay/v1/subscriptions"
+const routeRelayV1Messages = "/relay/v1/messages/{topic}"
 
+// RelayService represents the REST service for WakuRelay
 type RelayService struct {
 	node   *node.WakuNode
 	cancel context.CancelFunc
@@ -31,6 +33,7 @@ type RelayService struct {
 	runner *runnerService
 }
 
+// NewRelayService returns an instance of RelayService
 func NewRelayService(node *node.WakuNode, m *chi.Mux, cacheCapacity int, log *zap.Logger) *RelayService {
 	s := &RelayService{
 		node:          node,
@@ -41,10 +44,10 @@ func NewRelayService(node *node.WakuNode, m *chi.Mux, cacheCapacity int, log *za
 
 	s.runner = newRunnerService(node.Broadcaster(), s.addEnvelope)
 
-	m.Post(ROUTE_RELAY_SUBSCRIPTIONSV1, s.postV1Subscriptions)
-	m.Delete(ROUTE_RELAY_SUBSCRIPTIONSV1, s.deleteV1Subscriptions)
-	m.Get(ROUTE_RELAY_MESSAGESV1, s.getV1Messages)
-	m.Post(ROUTE_RELAY_MESSAGESV1, s.postV1Message)
+	m.Post(routeRelayV1Subscriptions, s.postV1Subscriptions)
+	m.Delete(routeRelayV1Subscriptions, s.deleteV1Subscriptions)
+	m.Get(routeRelayV1Messages, s.getV1Messages)
+	m.Post(routeRelayV1Messages, s.postV1Message)
 
 	return s
 }
@@ -65,6 +68,7 @@ func (r *RelayService) addEnvelope(envelope *protocol.Envelope) {
 	r.messages[envelope.PubsubTopic()] = append(r.messages[envelope.PubsubTopic()], envelope.Message())
 }
 
+// Start starts the RelayService
 func (r *RelayService) Start(ctx context.Context) {
 	ctx, cancel := context.WithCancel(ctx)
 	r.cancel = cancel
@@ -80,6 +84,7 @@ func (r *RelayService) Start(ctx context.Context) {
 	r.runner.Start(ctx)
 }
 
+// Stop stops the RelayService
 func (r *RelayService) Stop() {
 	if r.cancel == nil {
 		return
@@ -187,11 +192,23 @@ func (d *RelayService) postV1Message(w http.ResponseWriter, r *http.Request) {
 
 	var err error
 	if topic == "" {
-		_, err = d.node.Relay().Publish(r.Context(), message)
-	} else {
-		_, err = d.node.Relay().PublishToTopic(r.Context(), message, strings.Replace(topic, "\n", "", -1))
+		topic = relay.DefaultWakuTopic
 	}
 
+	if !d.node.Relay().IsSubscribed(topic) {
+		writeErrOrResponse(w, errors.New("not subscribed to pubsubTopic"), nil)
+		return
+	}
+
+	if node.SupportsRLN {
+		err = d.node.RLNRelay().AppendRLNProof(message, d.node.Timesource().Now())
+		if err != nil {
+			writeErrOrResponse(w, errors.New("not subscribed to pubsubTopic"), nil)
+			return
+		}
+	}
+
+	_, err = d.node.Relay().PublishToTopic(r.Context(), message, strings.Replace(topic, "\n", "", -1))
 	if err != nil {
 		d.log.Error("publishing message", zap.Error(err))
 	}
diff --git a/cmd/waku/rpc/relay.go b/cmd/waku/rpc/relay.go
index 8fce74cae..9f14d4e9e 100644
--- a/cmd/waku/rpc/relay.go
+++ b/cmd/waku/rpc/relay.go
@@ -1,6 +1,7 @@
 package rpc
 
 import (
+	"errors"
 	"fmt"
 	"net/http"
 	"sync"
@@ -12,6 +13,7 @@ import (
 	"go.uber.org/zap"
 )
 
+// RelayService represents the JSON RPC service for WakuRelay
 type RelayService struct {
 	node *node.WakuNode
 
@@ -24,19 +26,23 @@ type RelayService struct {
 	runner *runnerService
 }
 
+// RelayMessageArgs represents the requests used for posting messages
 type RelayMessageArgs struct {
 	Topic   string          `json:"topic,omitempty"`
 	Message *RPCWakuMessage `json:"message,omitempty"`
 }
 
+// TopicArgs represents the lists of topics to use when subscribing / unsubscribing
 type TopicsArgs struct {
 	Topics []string `json:"topics,omitempty"`
 }
 
+// TopicArgs represents a request that contains a single topic
 type TopicArgs struct {
 	Topic string `json:"topic,omitempty"`
 }
 
+// NewRelayService returns an instance of RelayService
 func NewRelayService(node *node.WakuNode, cacheCapacity int, log *zap.Logger) *RelayService {
 	s := &RelayService{
 		node:          node,
@@ -66,6 +72,7 @@ func (r *RelayService) addEnvelope(envelope *protocol.Envelope) {
 	r.messages[envelope.PubsubTopic()] = append(r.messages[envelope.PubsubTopic()], envelope.Message())
 }
 
+// Start starts the RelayService
 func (r *RelayService) Start() {
 	r.messagesMutex.Lock()
 	// Node may already be subscribed to some topics when Relay API handlers are installed. Let's add these
@@ -78,18 +85,34 @@ func (r *RelayService) Start() {
 	r.runner.Start()
 }
 
+// Stop stops the RelayService
 func (r *RelayService) Stop() {
 	r.runner.Stop()
 }
 
+// PostV1Message is invoked when the json rpc request uses the post_waku_v2_relay_v1_message method
 func (r *RelayService) PostV1Message(req *http.Request, args *RelayMessageArgs, reply *SuccessReply) error {
 	var err error
 
-	if args.Topic == "" {
-		_, err = r.node.Relay().Publish(req.Context(), args.Message.toProto())
-	} else {
-		_, err = r.node.Relay().PublishToTopic(req.Context(), args.Message.toProto(), args.Topic)
+	topic := relay.DefaultWakuTopic
+	if args.Topic != "" {
+		topic = args.Topic
 	}
+
+	if !r.node.Relay().IsSubscribed(topic) {
+		return errors.New("not subscribed to pubsubTopic")
+	}
+
+	msg := args.Message.toProto()
+
+	if node.SupportsRLN {
+		err = r.node.RLNRelay().AppendRLNProof(msg, r.node.Timesource().Now())
+		if err != nil {
+			return err
+		}
+	}
+
+	_, err = r.node.Relay().PublishToTopic(req.Context(), args.Message.toProto(), topic)
 	if err != nil {
 		r.log.Error("publishing message", zap.Error(err))
 		return err
@@ -99,6 +122,7 @@ func (r *RelayService) PostV1Message(req *http.Request, args *RelayMessageArgs,
 	return nil
 }
 
+// PostV1Subscription is invoked when the json rpc request uses the post_waku_v2_relay_v1_subscription method
 func (r *RelayService) PostV1Subscription(req *http.Request, args *TopicsArgs, reply *SuccessReply) error {
 	ctx := req.Context()
 	for _, topic := range args.Topics {
@@ -129,6 +153,7 @@ func (r *RelayService) PostV1Subscription(req *http.Request, args *TopicsArgs, r
 	return nil
 }
 
+// DeleteV1Subscription is invoked when the json rpc request uses the delete_waku_v2_relay_v1_subscription method
 func (r *RelayService) DeleteV1Subscription(req *http.Request, args *TopicsArgs, reply *SuccessReply) error {
 	ctx := req.Context()
 	for _, topic := range args.Topics {
@@ -145,6 +170,7 @@ func (r *RelayService) DeleteV1Subscription(req *http.Request, args *TopicsArgs,
 	return nil
 }
 
+// GetV1Messages is invoked when the json rpc request uses the get_waku_v2_relay_v1_messages method
 func (r *RelayService) GetV1Messages(req *http.Request, args *TopicArgs, reply *MessagesReply) error {
 	r.messagesMutex.Lock()
 	defer r.messagesMutex.Unlock()
diff --git a/waku/v2/node/wakunode2_no_rln.go b/waku/v2/node/wakunode2_no_rln.go
index 53620cda5..6356fc4fe 100644
--- a/waku/v2/node/wakunode2_no_rln.go
+++ b/waku/v2/node/wakunode2_no_rln.go
@@ -5,6 +5,9 @@ package node
 
 import "context"
 
+const SupportsRLN = false
+
+// RLNRelay is used to access any operation related to Waku RLN protocol
 func (w *WakuNode) RLNRelay() RLNRelay {
 	return nil
 }
diff --git a/waku/v2/node/wakunode2_rln.go b/waku/v2/node/wakunode2_rln.go
index 456ce396a..bcf69330a 100644
--- a/waku/v2/node/wakunode2_rln.go
+++ b/waku/v2/node/wakunode2_rln.go
@@ -16,6 +16,8 @@ import (
 	r "github.com/waku-org/go-zerokit-rln/rln"
 )
 
+const SupportsRLN = true
+
 // RLNRelay is used to access any operation related to Waku RLN protocol
 func (w *WakuNode) RLNRelay() RLNRelay {
 	return w.rlnRelay