diff --git a/dms.py b/dms.py
index a7aecd17..51c75050 100644
--- a/dms.py
+++ b/dms.py
@@ -107,6 +107,10 @@ def receive(*, from_user, obj):
         return 'OK', 200
 
     elif to_proto.owns_handle(content) is not False:
+        if not from_user.is_enabled(to_proto):
+            maybe_send(from_proto=to_proto, to_user=from_user, text=f'Please bridge your account to {to_proto.PHRASE} by following this account before requesting another user.')
+            return 'OK', 200
+
         if to_id := to_proto.handle_to_id(content):
             if to_user := to_proto.get_or_create(to_id):
                 maybe_send(from_proto=from_user, to_user=to_user,
@@ -116,3 +120,4 @@ def receive(*, from_user, obj):
 <p>Bridgy Fed will only send you this message once.""")
                 return 'OK', 200
 
+    return "Couldn't understand DM: foo bar", 304
diff --git a/tests/test_dms.py b/tests/test_dms.py
index ed00161c..a590a155 100644
--- a/tests/test_dms.py
+++ b/tests/test_dms.py
@@ -5,6 +5,14 @@ from web import Web
 
 from .testutil import ExplicitEnableFake, Fake, OtherFake, TestCase
 
+DM_EEFAKE_ALICE_REQUESTS_OTHER_BOB = {
+    'objectType': 'note',
+    'id': 'eefake:dm',
+    'actor': 'eefake:alice',
+    'to': ['other.brid.gy'],
+    'content': ' other:handle:bob ',
+}
+
 
 class DmsTest(TestCase):
     def test_maybe_send(self):
@@ -56,7 +64,19 @@ class DmsTest(TestCase):
         self.assertEqual([], OtherFake.sent)
         self.assertEqual([], user.sent_dms)
 
-    # def test_receive_unknown_text(self):
+    def test_receive_unknown_text(self):
+        self.make_user(id='other.brid.gy', cls=Web)
+        alice = self.make_user('eefake:alice', cls=ExplicitEnableFake,
+                               enabled_protocols=['other'], obj_id='eefake:alice')
+
+        obj = Object(our_as1={
+            **DM_EEFAKE_ALICE_REQUESTS_OTHER_BOB,
+            'content': 'foo bar',
+        })
+        self.assertEqual(("Couldn't understand DM: foo bar", 304),
+                         receive(from_user=alice, obj=obj))
+        self.assertEqual([], OtherFake.sent)
+        self.assertEqual([], Fake.sent)
 
     def test_receive_no_yes_sets_enabled_protocols(self):
         alice = self.make_user('fake:alice', cls=Fake, obj_id='fake:alice')
@@ -115,31 +135,46 @@ class DmsTest(TestCase):
             Fake.sent)
 
     def test_receive_handle_sends_request_dm(self):
-        self.make_user(id='other.brid.gy', cls=Web)
         self.make_user(id='eefake.brid.gy', cls=Web)
         alice = self.make_user(id='eefake:alice', cls=ExplicitEnableFake,
                                enabled_protocols=['other'], obj_as1={'x': 'y'})
         bob = self.make_user(id='other:bob', cls=OtherFake, obj_as1={'x': 'y'})
 
-        dm = Object(our_as1={
-            'objectType': 'note',
-            'id': 'eefake:dm',
-            'actor': 'eefake:alice',
-            'to': ['other.brid.gy'],
-            'content': ' other:handle:bob ',
-        })
-        self.assertEqual(('OK', 200), receive(from_user=alice, obj=dm))
+        obj = Object(our_as1=DM_EEFAKE_ALICE_REQUESTS_OTHER_BOB)
+        self.assertEqual(('OK', 200), receive(from_user=alice, obj=obj))
         self.assertEqual(
             [('https://eefake.brid.gy/#request_bridging-dm-other:bob-2022-01-02T03:04:05+00:00',
               'other:bob:target')],
             OtherFake.sent)
 
-    # def test_receive_handle_from_user_not_bridged(self):
+    def test_receive_handle_from_user_not_bridged(self):
+        self.make_user(id='other.brid.gy', cls=Web)
+        # Alice isn't bridged into OtherFake
+        alice = self.make_user(id='eefake:alice', cls=ExplicitEnableFake,
+                               enabled_protocols=['fake'], obj_as1={'x': 'y'})
+        self.make_user(id='other:bob', cls=OtherFake, obj_as1={'x': 'y'})
+
+        obj = Object(our_as1=DM_EEFAKE_ALICE_REQUESTS_OTHER_BOB)
+        self.assertEqual(('OK', 200), receive(from_user=alice, obj=obj))
+        self.assertEqual([], OtherFake.sent)
+        self.assertEqual([], Fake.sent)
 
     # def test_receive_handle_already_bridged(self):
 
+    # def test_receive_handle_already_requested(self):
+
+    def test_receive_handle_wrong_protocol(self):
+        self.make_user(id='other.brid.gy', cls=Web)
+
+        obj = Object(our_as1={
+            **DM_EEFAKE_ALICE_REQUESTS_OTHER_BOB,
+                             'content': 'fake:eve',
+        })
+        self.assertEqual(("Couldn't understand DM: foo bar", 304),
+                         receive(from_user=Fake(id='fake:user'), obj=obj))
+        self.assertEqual([], OtherFake.sent)
+        self.assertEqual([], Fake.sent)
+
     # def test_receive_handle_fetch_user(self):
 
-    # def test_receive_handle_wrong_protocol(self):
-
     # def test_receive_handle_user_doesnt_exist(self):