diff --git a/synapse/api/auth.py b/synapse/api/auth.py
index 4f028078fa272dd2c152f171d76d2592b91ff62a..9c62ec43742df7a8d53e50240392ea49f3ee39c2 100644
--- a/synapse/api/auth.py
+++ b/synapse/api/auth.py
@@ -781,15 +781,11 @@ class Auth(object):
         """
         if self.hs.config.hs_disabled:
             raise AuthError(
-                403, self.hs.config.hs_disabled_message,
-                errcode=Codes.HS_DISABLED,
-                admin_email=self.hs.config.admin_email,
+                403, self.hs.config.hs_disabled_message, errcode=Codes.HS_DISABLED
             )
         if self.hs.config.limit_usage_by_mau is True:
             current_mau = yield self.store.get_monthly_active_count()
             if current_mau >= self.hs.config.max_mau_value:
                 raise AuthError(
-                    403, "MAU Limit Exceeded",
-                    admin_email=self.hs.config.admin_email,
-                    errcode=Codes.MAU_LIMIT_EXCEEDED
+                    403, "MAU Limit Exceeded", errcode=Codes.MAU_LIMIT_EXCEEDED
                 )
diff --git a/synapse/api/errors.py b/synapse/api/errors.py
index d74848159e44dbff84f2fe56c727599cd8972937..dc3bed5fcbbd7dcedc6b4698af61652a22c9759f 100644
--- a/synapse/api/errors.py
+++ b/synapse/api/errors.py
@@ -225,20 +225,11 @@ class NotFoundError(SynapseError):
 
 class AuthError(SynapseError):
     """An error raised when there was a problem authorising an event."""
+
     def __init__(self, *args, **kwargs):
         if "errcode" not in kwargs:
             kwargs["errcode"] = Codes.FORBIDDEN
-        self.admin_email = kwargs.get('admin_email')
-        self.msg = kwargs.get('msg')
-        self.errcode = kwargs.get('errcode')
-        super(AuthError, self).__init__(*args, errcode=kwargs["errcode"])
-
-    def error_dict(self):
-        return cs_error(
-            self.msg,
-            self.errcode,
-            admin_email=self.admin_email,
-        )
+        super(AuthError, self).__init__(*args, **kwargs)
 
 
 class EventSizeError(SynapseError):
diff --git a/synapse/config/server.py b/synapse/config/server.py
index 64a5121a452f40482bb6c5c11a62eede1b59c534..3b078d72cabd7dc0af19a05f0c8767582e0f1687 100644
--- a/synapse/config/server.py
+++ b/synapse/config/server.py
@@ -82,10 +82,6 @@ class ServerConfig(Config):
         self.hs_disabled = config.get("hs_disabled", False)
         self.hs_disabled_message = config.get("hs_disabled_message", "")
 
-        # Admin email to direct users at should their instance become blocked
-        # due to resource constraints
-        self.admin_email = config.get("admin_email", None)
-
         # FIXME: federation_domain_whitelist needs sytests
         self.federation_domain_whitelist = None
         federation_domain_whitelist = config.get(
diff --git a/synapse/handlers/register.py b/synapse/handlers/register.py
index ef7222d7b86011c31ed6023f5d1868eaa7d91ba3..3526b20d5a574e5d055d962b45e469a14a5dd24a 100644
--- a/synapse/handlers/register.py
+++ b/synapse/handlers/register.py
@@ -144,8 +144,7 @@ class RegistrationHandler(BaseHandler):
         Raises:
             RegistrationError if there was a problem registering.
         """
-
-        yield self.auth.check_auth_blocking()
+        yield self._check_mau_limits()
         password_hash = None
         if password:
             password_hash = yield self.auth_handler().hash(password)
@@ -290,7 +289,7 @@ class RegistrationHandler(BaseHandler):
                 400,
                 "User ID can only contain characters a-z, 0-9, or '=_-./'",
             )
-        yield self.auth.check_auth_blocking()
+        yield self._check_mau_limits()
         user = UserID(localpart, self.hs.hostname)
         user_id = user.to_string()
 
@@ -440,7 +439,7 @@ class RegistrationHandler(BaseHandler):
         """
         if localpart is None:
             raise SynapseError(400, "Request must include user id")
-        yield self.auth.check_auth_blocking()
+        yield self._check_mau_limits()
         need_register = True
 
         try:
@@ -535,13 +534,13 @@ class RegistrationHandler(BaseHandler):
             action="join",
         )
 
-    # @defer.inlineCallbacks
-    # def _s(self):
-    #     """
-    #     Do not accept registrations if monthly active user limits exceeded
-    #      and limiting is enabled
-    #     """
-    #     try:
-    #         yield self.auth.check_auth_blocking()
-    #     except AuthError as e:
-    #         raise RegistrationError(e.code, str(e), e.errcode)
+    @defer.inlineCallbacks
+    def _check_mau_limits(self):
+        """
+        Do not accept registrations if monthly active user limits exceeded
+         and limiting is enabled
+        """
+        try:
+            yield self.auth.check_auth_blocking()
+        except AuthError as e:
+            raise RegistrationError(e.code, str(e), e.errcode)
diff --git a/tests/api/test_auth.py b/tests/api/test_auth.py
index e8a1894e651c3ebfa97c4a4f77c4f837daf62106..a65689ba896e5d8037404903eb95c6e71bbcf074 100644
--- a/tests/api/test_auth.py
+++ b/tests/api/test_auth.py
@@ -455,11 +455,8 @@ class AuthTestCase(unittest.TestCase):
             return_value=defer.succeed(lots_of_users)
         )
 
-        with self.assertRaises(AuthError) as e:
+        with self.assertRaises(AuthError):
             yield self.auth.check_auth_blocking()
-        self.assertEquals(e.exception.admin_email, self.hs.config.admin_email)
-        self.assertEquals(e.exception.errcode, Codes.MAU_LIMIT_EXCEEDED)
-        self.assertEquals(e.exception.code, 403)
 
         # Ensure does not throw an error
         self.store.get_monthly_active_count = Mock(
@@ -473,6 +470,5 @@ class AuthTestCase(unittest.TestCase):
         self.hs.config.hs_disabled_message = "Reason for being disabled"
         with self.assertRaises(AuthError) as e:
             yield self.auth.check_auth_blocking()
-        self.assertEquals(e.exception.admin_email, self.hs.config.admin_email)
         self.assertEquals(e.exception.errcode, Codes.HS_DISABLED)
         self.assertEquals(e.exception.code, 403)
diff --git a/tests/handlers/test_register.py b/tests/handlers/test_register.py
index 35d1bcab3e9f913d67b8bce0d8f5c56b7c622b89..d48d40c8dd97d1ab6fd3b6504e949fb91f73e66b 100644
--- a/tests/handlers/test_register.py
+++ b/tests/handlers/test_register.py
@@ -17,7 +17,7 @@ from mock import Mock
 
 from twisted.internet import defer
 
-from synapse.api.errors import AuthError
+from synapse.api.errors import RegistrationError
 from synapse.handlers.register import RegistrationHandler
 from synapse.types import UserID, create_requester
 
@@ -109,7 +109,7 @@ class RegistrationTestCase(unittest.TestCase):
         self.store.get_monthly_active_count = Mock(
             return_value=defer.succeed(self.lots_of_users)
         )
-        with self.assertRaises(AuthError):
+        with self.assertRaises(RegistrationError):
             yield self.handler.get_or_create_user("requester", 'b', "display_name")
 
     @defer.inlineCallbacks
@@ -118,7 +118,7 @@ class RegistrationTestCase(unittest.TestCase):
         self.store.get_monthly_active_count = Mock(
             return_value=defer.succeed(self.lots_of_users)
         )
-        with self.assertRaises(AuthError):
+        with self.assertRaises(RegistrationError):
             yield self.handler.register(localpart="local_part")
 
     @defer.inlineCallbacks
@@ -127,5 +127,5 @@ class RegistrationTestCase(unittest.TestCase):
         self.store.get_monthly_active_count = Mock(
             return_value=defer.succeed(self.lots_of_users)
         )
-        with self.assertRaises(AuthError):
+        with self.assertRaises(RegistrationError):
             yield self.handler.register_saml2(localpart="local_part")
diff --git a/tests/utils.py b/tests/utils.py
index 4af81624eb39c1302b383be53c4c9eb3e328558c..90378326f89844001f3ed818e4e370b867ed5452 100644
--- a/tests/utils.py
+++ b/tests/utils.py
@@ -139,7 +139,6 @@ def setup_test_homeserver(
         config.hs_disabled_message = ""
         config.max_mau_value = 50
         config.mau_limits_reserved_threepids = []
-        config.admin_email = None
 
         # we need a sane default_room_version, otherwise attempts to create rooms will
         # fail.