diff --git a/nostr/message_pool.py b/nostr/message_pool.py
index d364cf2..21895b9 100644
--- a/nostr/message_pool.py
+++ b/nostr/message_pool.py
@@ -24,11 +24,18 @@ class EndOfStoredEventsMessage:
         self.url = url
 
 
+class AuthMessage:
+    def __init__(self, challenge: str, url: str) -> None:
+        self.challenge = challenge
+        self.url = url
+
+
 class MessagePool:
     def __init__(self) -> None:
         self.events: Queue[EventMessage] = Queue()
         self.notices: Queue[NoticeMessage] = Queue()
         self.eose_notices: Queue[EndOfStoredEventsMessage] = Queue()
+        self.auths: Queue[AuthMessage] = Queue()
         self._unique_events: set = set()
         self.lock: Lock = Lock()
 
@@ -44,6 +51,9 @@ class MessagePool:
     def get_eose_notice(self):
         return self.eose_notices.get()
 
+    def get_auth(self):
+        return self.auth.get()
+
     def has_events(self):
         return self.events.qsize() > 0
 
@@ -53,6 +63,9 @@ class MessagePool:
     def has_eose_notices(self):
         return self.eose_notices.qsize() > 0
 
+    def has_auths(self):
+        return self.auths.qsize() > 0
+
     def _process_message(self, message: str, url: str):
         message_json = json.loads(message)
         message_type = message_json[0]
@@ -75,3 +88,5 @@ class MessagePool:
             self.notices.put(NoticeMessage(message_json[1], url))
         elif message_type == RelayMessageType.END_OF_STORED_EVENTS:
             self.eose_notices.put(EndOfStoredEventsMessage(message_json[1], url))
+        elif message_type == RelayMessageType.AUTH:
+            self.auths.put(AuthMessage(message_json[1], url))
diff --git a/nostr/message_type.py b/nostr/message_type.py
index 3f5206b..0ff30e8 100644
--- a/nostr/message_type.py
+++ b/nostr/message_type.py
@@ -2,14 +2,16 @@ class ClientMessageType:
     EVENT = "EVENT"
     REQUEST = "REQ"
     CLOSE = "CLOSE"
+    AUTH = "AUTH"
 
 class RelayMessageType:
     EVENT = "EVENT"
     NOTICE = "NOTICE"
     END_OF_STORED_EVENTS = "EOSE"
+    AUTH = "AUTH"
 
     @staticmethod
     def is_valid(type: str) -> bool:
         if type == RelayMessageType.EVENT or type == RelayMessageType.NOTICE or type == RelayMessageType.END_OF_STORED_EVENTS:
             return True
-        return False
\ No newline at end of file
+        return False
diff --git a/nostr/relay.py b/nostr/relay.py
index ee78baa..670480c 100644
--- a/nostr/relay.py
+++ b/nostr/relay.py
@@ -100,7 +100,7 @@ class Relay:
 
     def close_subscription(self, id: str) -> None:
         with self.lock:
-            self.subscriptions.pop(id)
+            self.subscriptions.pop(id, None)
 
     def update_subscription(self, id: str, filters: Filters) -> None:
         with self.lock:
diff --git a/nostr/relay_manager.py b/nostr/relay_manager.py
index 5b92d8d..48df278 100644
--- a/nostr/relay_manager.py
+++ b/nostr/relay_manager.py
@@ -52,12 +52,13 @@ class RelayManager:
         for relay in self.relays.values():
             relay.close()
 
-    def publish_message(self, message: str):
+    def publish_message(self, message: str, url:str=None):
         for relay in self.relays.values():
             if relay.policy.should_write:
-                relay.publish(message)
+                if url is None or relay.url == url:
+                    relay.publish(message)
 
-    def publish_event(self, event: Event):
+    def verify_event(self, event: Event):
         """Verifies that the Event is publishable before submitting it to relays"""
         if event.signature is None:
             raise RelayException(f"Could not publish {event.id}: must be signed")
@@ -66,4 +67,12 @@ class RelayManager:
             raise RelayException(
                 f"Could not publish {event.id}: failed to verify signature {event.signature}"
             )
+
+    def publish_event(self, event: Event):
+        self.verify_event(event)
         self.publish_message(event.to_message())
+
+    def publish_auth(self, event: Event, url: str):
+        self.verify_event(event)
+        self.publish_message(event.to_message(), url)
+