diff --git a/synapse/rest/client/v2_alpha/account.py b/synapse/rest/client/v2_alpha/account.py
index d085951b23..e1745fad2d 100644
--- a/synapse/rest/client/v2_alpha/account.py
+++ b/synapse/rest/client/v2_alpha/account.py
@@ -55,7 +55,7 @@ class EmailPasswordRequestTokenRestServlet(RestServlet):
         if not (yield check_3pid_allowed(self.hs, "email", body['email'])):
             raise SynapseError(
                 403,
-                "Your email domain is not authorized on this server",
+                "Your email is not authorized on this server",
                 Codes.THREEPID_DENIED,
             )
 
@@ -271,7 +271,7 @@ class EmailThreepidRequestTokenRestServlet(RestServlet):
         if not (yield check_3pid_allowed(self.hs, "email", body['email'])):
             raise SynapseError(
                 403,
-                "Your email domain is not authorized on this server",
+                "Your email is not authorized on this server",
                 Codes.THREEPID_DENIED,
             )
 
diff --git a/synapse/rest/client/v2_alpha/register.py b/synapse/rest/client/v2_alpha/register.py
index fb9441a87a..cf1b70e39e 100644
--- a/synapse/rest/client/v2_alpha/register.py
+++ b/synapse/rest/client/v2_alpha/register.py
@@ -78,7 +78,7 @@ class EmailRegisterRequestTokenRestServlet(RestServlet):
         if not (yield check_3pid_allowed(self.hs, "email", body['email'])):
             raise SynapseError(
                 403,
-                "Your email domain is not authorized to register on this server",
+                "Your email is not authorized to register on this server",
                 Codes.THREEPID_DENIED,
             )
 
diff --git a/synapse/util/threepids.py b/synapse/util/threepids.py
index 353d220bad..4f3cb9c804 100644
--- a/synapse/util/threepids.py
+++ b/synapse/util/threepids.py
@@ -23,7 +23,7 @@ logger = logging.getLogger(__name__)
 
 @defer.inlineCallbacks
 def check_3pid_allowed(hs, medium, address):
-    """Checks whether a given format of 3PID is allowed to be used on this HS
+    """Checks whether a given 3PID is allowed to be used on this HS
 
     Args:
         hs (synapse.server.HomeServer): server
@@ -38,10 +38,18 @@ def check_3pid_allowed(hs, medium, address):
         data = yield hs.get_simple_http_client().get_json(
             "https://%s%s" % (
                 hs.config.check_is_for_allowed_local_3pids,
-                "/_matrix/identity/api/v1/info"
+                "/_matrix/identity/api/v1/internal-info"
             ),
             {'medium': medium, 'address': address}
         )
+
+        # Assume false if invalid response
+        if 'hs' not in data:
+            defer.returnValue(False)
+
+        if data.get('requires_invite', False) and data.get('invited', False) == False:
+            # Requires an invite but hasn't been invited
+            defer.returnValue(False)
         if hs.config.allow_invited_3pids and data.get('invited'):
             defer.returnValue(True)
         else: