diff --git a/packages/common/src/enums/index.ts b/packages/common/src/enums/index.ts
index 6ea9a367..f0511a29 100644
--- a/packages/common/src/enums/index.ts
+++ b/packages/common/src/enums/index.ts
@@ -1,4 +1,3 @@
 export * from './client.enum';
 export * from './event.enum';
 export * from './log.enum';
-export * from './message.enum';
diff --git a/packages/common/src/enums/message.enum.ts b/packages/common/src/enums/message.enum.ts
deleted file mode 100644
index 71deba00..00000000
--- a/packages/common/src/enums/message.enum.ts
+++ /dev/null
@@ -1,12 +0,0 @@
-/**
- * Message types
- */
-export enum MessageType {
-  REQ = 'REQ',
-  EVENT = 'EVENT',
-  CLOSE = 'CLOSE',
-  AUTH = 'AUTH',
-  EOSE = 'EOSE',
-  OK = 'OK',
-  NOTICE = 'NOTICE',
-}
diff --git a/packages/common/src/interfaces/message.interface.ts b/packages/common/src/interfaces/message.interface.ts
index 44c58700..f159c418 100644
--- a/packages/common/src/interfaces/message.interface.ts
+++ b/packages/common/src/interfaces/message.interface.ts
@@ -1,15 +1,18 @@
-import { MessageType } from '../enums';
 import { EventId, SubscriptionId } from './common.interface';
 import { Event } from './event.interface';
 import { Filter } from './filter.interface';
 
-export type MessageTypeEvent = MessageType.EVENT | 'EVENT';
-export type MessageTypeReq = MessageType.REQ | 'REQ';
-export type MessageTypeClose = MessageType.CLOSE | 'CLOSE';
-export type MessageTypeAuth = MessageType.AUTH | 'AUTH';
-export type MessageTypeOk = MessageType.OK | 'OK';
-export type MessageTypeEose = MessageType.EOSE | 'EOSE';
-export type MessageTypeNotice = MessageType.NOTICE | 'NOTICE';
+export const MessageType = {
+  REQ: 'REQ',
+  EVENT: 'EVENT',
+  CLOSE: 'CLOSE',
+  AUTH: 'AUTH',
+  EOSE: 'EOSE',
+  OK: 'OK',
+  NOTICE: 'NOTICE',
+  CLOSED: 'CLOSED',
+} as const;
+export type TMessageType = (typeof MessageType)[keyof typeof MessageType];
 
 export type IncomingMessage =
   | IncomingEventMessage
@@ -17,20 +20,39 @@ export type IncomingMessage =
   | IncomingCloseMessage
   | IncomingAuthMessage;
 
-export type IncomingEventMessage = [MessageTypeEvent, Event];
-export type IncomingReqMessage = [MessageTypeReq, SubscriptionId, ...Filter[]];
-export type IncomingCloseMessage = [MessageTypeClose, SubscriptionId];
-export type IncomingAuthMessage = [MessageTypeAuth, Event];
+export type IncomingEventMessage = [typeof MessageType.EVENT, Event];
+export type IncomingReqMessage = [
+  typeof MessageType.REQ,
+  SubscriptionId,
+  ...Filter[],
+];
+export type IncomingCloseMessage = [typeof MessageType.CLOSE, SubscriptionId];
+export type IncomingAuthMessage = [typeof MessageType.AUTH, Event];
 
 export type OutgoingMessage =
   | OutgoingOkMessage
   | OutgoingEventMessage
   | OutgoingEoseMessage
   | OutgoingNoticeMessage
-  | OutgoingAuthMessage;
+  | OutgoingAuthMessage
+  | OutgoingClosedMessage;
 
-export type OutgoingOkMessage = [MessageTypeOk, EventId, boolean, string];
-export type OutgoingEventMessage = [MessageTypeEvent, SubscriptionId, Event];
-export type OutgoingEoseMessage = [MessageTypeEose, SubscriptionId];
-export type OutgoingNoticeMessage = [MessageTypeNotice, string];
-export type OutgoingAuthMessage = [MessageTypeAuth, string];
+export type OutgoingOkMessage = [
+  typeof MessageType.OK,
+  EventId,
+  boolean,
+  string,
+];
+export type OutgoingEventMessage = [
+  typeof MessageType.EVENT,
+  SubscriptionId,
+  Event,
+];
+export type OutgoingEoseMessage = [typeof MessageType.EOSE, SubscriptionId];
+export type OutgoingNoticeMessage = [typeof MessageType.NOTICE, string];
+export type OutgoingAuthMessage = [typeof MessageType.AUTH, string];
+export type OutgoingClosedMessage = [
+  typeof MessageType.CLOSED,
+  SubscriptionId,
+  string,
+];
diff --git a/packages/core/__test__/nostr-relay.spec.ts b/packages/core/__test__/nostr-relay.spec.ts
index 3738879b..3f0ad17c 100644
--- a/packages/core/__test__/nostr-relay.spec.ts
+++ b/packages/core/__test__/nostr-relay.spec.ts
@@ -228,12 +228,18 @@ describe('NostrRelay', () => {
       );
 
       expect(result).toEqual({ events: [] });
-      expect(client.send).toHaveBeenCalledWith(
+      expect(client.send).toHaveBeenNthCalledWith(
+        1,
         JSON.stringify([
-          MessageType.NOTICE,
+          MessageType.CLOSED,
+          subscriptionId,
           "restricted: we can't serve DMs to unauthenticated users, does your client implement NIP-42?",
         ]),
       );
+      expect(client.send).toHaveBeenNthCalledWith(
+        2,
+        JSON.stringify([MessageType.AUTH, ctx.id]),
+      );
     });
 
     it('should handle req successfully if client is authenticated and filter contains encrypted direct message kind', async () => {
diff --git a/packages/core/src/interfaces/handle-result.interface.ts b/packages/core/src/interfaces/handle-result.interface.ts
index e9d4c7ac..76974529 100644
--- a/packages/core/src/interfaces/handle-result.interface.ts
+++ b/packages/core/src/interfaces/handle-result.interface.ts
@@ -85,8 +85,8 @@ export type HandleAuthMessageResult = {
  * Result of handling an incoming message
  */
 export type HandleMessageResult =
-  | ({ messageType: MessageType.REQ } & HandleReqMessageResult)
-  | ({ messageType: MessageType.EVENT } & HandleEventMessageResult)
-  | ({ messageType: MessageType.CLOSE } & HandleCloseMessageResult)
-  | ({ messageType: MessageType.AUTH } & HandleAuthMessageResult)
+  | ({ messageType: typeof MessageType.REQ } & HandleReqMessageResult)
+  | ({ messageType: typeof MessageType.EVENT } & HandleEventMessageResult)
+  | ({ messageType: typeof MessageType.CLOSE } & HandleCloseMessageResult)
+  | ({ messageType: typeof MessageType.AUTH } & HandleAuthMessageResult)
   | void;
diff --git a/packages/core/src/nostr-relay.ts b/packages/core/src/nostr-relay.ts
index d27ffd7d..19939a6a 100644
--- a/packages/core/src/nostr-relay.ts
+++ b/packages/core/src/nostr-relay.ts
@@ -29,6 +29,7 @@ import { SubscriptionService } from './services/subscription.service';
 import {
   LazyCache,
   createOutgoingAuthMessage,
+  createOutgoingClosedMessage,
   createOutgoingEoseMessage,
   createOutgoingEventMessage,
   createOutgoingNoticeMessage,
@@ -252,10 +253,12 @@ export class NostrRelay {
       !ctx.pubkey
     ) {
       ctx.sendMessage(
-        createOutgoingNoticeMessage(
+        createOutgoingClosedMessage(
+          subscriptionId,
           "restricted: we can't serve DMs to unauthenticated users, does your client implement NIP-42?",
         ),
       );
+      ctx.sendMessage(createOutgoingAuthMessage(ctx.id));
       return { events };
     }
 
diff --git a/packages/core/src/utils/response.ts b/packages/core/src/utils/response.ts
index 7bc5c604..12472757 100644
--- a/packages/core/src/utils/response.ts
+++ b/packages/core/src/utils/response.ts
@@ -2,6 +2,7 @@ import {
   Event,
   MessageType,
   OutgoingAuthMessage,
+  OutgoingClosedMessage,
   OutgoingEoseMessage,
   OutgoingEventMessage,
   OutgoingNoticeMessage,
@@ -74,3 +75,17 @@ export function createOutgoingAuthMessage(
 ): OutgoingAuthMessage {
   return [MessageType.AUTH, challenge];
 }
+
+/**
+ * Create an outgoing CLOSED message.
+ * More info: https://github.com/nostr-protocol/nips/blob/master/01.md
+ *
+ * @param subscriptionId Subscription Id
+ * @param message Reason for closing the subscription
+ */
+export function createOutgoingClosedMessage(
+  subscriptionId: SubscriptionId,
+  message = '',
+): OutgoingClosedMessage {
+  return [MessageType.CLOSED, subscriptionId, message];
+}