1 files changed, 17 insertions, 3 deletions
diff --git a/synapse/api/auth.py b/synapse/api/auth.py
index 9c62ec4374..3b2a2ab77a 100644
--- a/synapse/api/auth.py
+++ b/synapse/api/auth.py
@@ -775,17 +775,31 @@ class Auth(object):
             )
 
     @defer.inlineCallbacks
-    def check_auth_blocking(self):
+    def check_auth_blocking(self, user_id=None):
         """Checks if the user should be rejected for some external reason,
         such as monthly active user limiting or global disable flag
+
+        Args:
+            user_id(str|None): If present, checks for presence against existing
+            MAU cohort
         """
         if self.hs.config.hs_disabled:
             raise AuthError(
-                403, self.hs.config.hs_disabled_message, errcode=Codes.HS_DISABLED
+                403, self.hs.config.hs_disabled_message,
+                errcode=Codes.RESOURCE_LIMIT_EXCEED,
+                admin_uri=self.hs.config.admin_uri,
             )
         if self.hs.config.limit_usage_by_mau is True:
+            # If the user is already part of the MAU cohort
+            if user_id:
+                timestamp = yield self.store.user_last_seen_monthly_active(user_id)
+                if timestamp:
+                    return
+            # Else if there is no room in the MAU bucket, bail
             current_mau = yield self.store.get_monthly_active_count()
             if current_mau >= self.hs.config.max_mau_value:
                 raise AuthError(
-                    403, "MAU Limit Exceeded", errcode=Codes.MAU_LIMIT_EXCEEDED
+                    403, "Monthly Active User Limits AU Limit Exceeded",
+                    admin_uri=self.hs.config.admin_uri,
+                    errcode=Codes.RESOURCE_LIMIT_EXCEED
                 )