diff --git a/letsencrypt/client.py b/letsencrypt/client.py
index 58e9c8e9f..3d611f856 100644
--- a/letsencrypt/client.py
+++ b/letsencrypt/client.py
@@ -146,8 +146,7 @@ def perform_registration(acme, config):
     try:
         return acme.register(messages.NewRegistration.from_data(email=config.email))
     except messages.Error as e:
-        err = repr(e)
-        if "MX record" in err or "Validation of contact mailto" in err:
+        if e.typ == "urn:acme:error:invalidEmail":
             config.namespace.email = display_ops.get_email(more=True, invalid=True)
             return perform_registration(acme, config)
         else:
diff --git a/letsencrypt/tests/client_test.py b/letsencrypt/tests/client_test.py
index 7dd513e18..1395a4f8f 100644
--- a/letsencrypt/tests/client_test.py
+++ b/letsencrypt/tests/client_test.py
@@ -63,8 +63,8 @@ class RegisterTest(unittest.TestCase):
     @mock.patch("letsencrypt.client.display_ops.get_email")
     def test_email_retry(self, _rep, mock_get_email):
         from acme import messages
-        msg = "Validation of contact mailto:sousaphone@improbablylongggstring.tld failed"
-        mx_err = messages.Error(detail=msg, typ="malformed", title="title")
+        msg = "DNS problem: NXDOMAIN looking up MX for example.com"
+        mx_err = messages.Error(detail=msg, typ="urn:acme:error:invalidEmail")
         with mock.patch("letsencrypt.client.acme_client.Client") as mock_client:
             mock_client().register.side_effect = [mx_err, mock.MagicMock()]
             self._call()