1 files changed, 8 insertions, 4 deletions
diff --git a/synapse/rest/client/v1/login.py b/synapse/rest/client/v1/login.py
index bf0f9bd077..f6eef7afee 100644
--- a/synapse/rest/client/v1/login.py
+++ b/synapse/rest/client/v1/login.py
@@ -28,6 +28,7 @@ from synapse.rest.client.v2_alpha._base import client_patterns
 from synapse.rest.well_known import WellKnownBuilder
 from synapse.types import UserID
 from synapse.util.msisdn import phone_number_to_msisdn
+from synapse.util.threepids import canonicalise_email
 
 logger = logging.getLogger(__name__)
 
@@ -206,11 +207,14 @@ class LoginRestServlet(RestServlet):
             if medium is None or address is None:
                 raise SynapseError(400, "Invalid thirdparty identifier")
 
+            # For emails, canonicalise the address.
+            # We store all email addresses canonicalised in the DB.
+            # (See add_threepid in synapse/handlers/auth.py)
             if medium == "email":
-                # For emails, transform the address to lowercase.
-                # We store all email addreses as lowercase in the DB.
-                # (See add_threepid in synapse/handlers/auth.py)
-                address = address.lower()
+                try:
+                    address = canonicalise_email(address)
+                except ValueError as e:
+                    raise SynapseError(400, str(e))
 
             # We also apply account rate limiting using the 3PID as a key, as
             # otherwise using 3PID bypasses the ratelimiting based on user ID.