diff --git a/synapse/handlers/auth.py b/synapse/handlers/auth.py
index dc0fe60e1..363552123 100644
--- a/synapse/handlers/auth.py
+++ b/synapse/handlers/auth.py
@@ -611,6 +611,18 @@ class AuthHandler(BaseHandler):
 
     @defer.inlineCallbacks
     def add_threepid(self, user_id, medium, address, validated_at):
+        # 'Canonicalise' email addresses down to lower case.
+        # We've now moving towards the Home Server being the entity that
+        # is responsible for validating threepids used for resetting passwords
+        # on accounts, so in future Synapse will gain knowledge of specific
+        # types (mediums) of threepid. For now, we still use the existing
+        # infrastructure, but this is the start of synapse gaining knowledge
+        # of specific types of threepid (and fixes the fact that checking
+        # for the presenc eof an email address during password reset was
+        # case sensitive).
+        if medium == 'email':
+            address = address.lower()
+
         yield self.store.user_add_threepid(
             user_id, medium, address, validated_at,
             self.hs.get_clock().time_msec()
diff --git a/synapse/storage/schema/delta/37/user_threepids.sql b/synapse/storage/schema/delta/37/user_threepids.sql
new file mode 100644
index 000000000..ef8813e72
--- /dev/null
+++ b/synapse/storage/schema/delta/37/user_threepids.sql
@@ -0,0 +1,23 @@
+/* Copyright 2016 OpenMarket Ltd
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/*
+ * Update any email addresses that were stored with mixed case into all
+ * lowercase
+ */
+UPDATE user_threepids SET address = LOWER(address) where medium = 'email';
+
+/* Add an index for the select we do on passwored reset */
+CREATE INDEX user_threepids_medium_address on user_threepids (medium, address);