diff --git a/zerver/lib/actions.py b/zerver/lib/actions.py
index b72d78df25..6c0b1afb91 100644
--- a/zerver/lib/actions.py
+++ b/zerver/lib/actions.py
@@ -1153,6 +1153,20 @@ def do_send_messages(messages_maybe_none):
             presence_idle_user_ids=presence_idle_user_ids,
         )
 
+        '''
+        TODO:  We may want to limit user_ids to only those users who have
+               UserMessage rows, if only for minor performance reasons.
+
+               For now we queue events for all subscribers/sendees of the
+               message, since downstream code may still do notifications
+               that don't require UserMessage rows.
+
+               Our automated tests have gotten better on this codepath,
+               but we may have coverage gaps, so we should be careful
+               about changing the next line.
+        '''
+        user_ids = message['active_user_ids'] | set(user_flags.keys())
+
         users = [
             dict(
                 id=user_id,
@@ -1160,7 +1174,7 @@ def do_send_messages(messages_maybe_none):
                 always_push_notify=(user_id in message['push_notify_user_ids']),
                 stream_push_notify=(user_id in message['stream_push_user_ids']),
             )
-            for user_id in message['active_user_ids']
+            for user_id in user_ids
         ]
 
         if message['message'].is_stream_message():
diff --git a/zerver/tests/test_messages.py b/zerver/tests/test_messages.py
index adda4dc8d0..f5632d1acf 100644
--- a/zerver/tests/test_messages.py
+++ b/zerver/tests/test_messages.py
@@ -68,7 +68,7 @@ import DNS
 import mock
 import time
 import ujson
-from typing import Any, Dict, List, Optional, Text
+from typing import Any, Dict, List, Optional, Set, Text
 
 from collections import namedtuple
 
@@ -593,6 +593,19 @@ class StreamMessagesTest(ZulipTestCase):
         message = most_recent_message(user_profile)
         assert(UserMessage.objects.get(user_profile=user_profile, message=message).flags.mentioned.is_set)
 
+    def _send_stream_message(self, email, stream_name, content):
+        # type: (Text, Text, Text) -> Set[int]
+        with mock.patch('zerver.lib.actions.send_event') as m:
+            self.send_stream_message(
+                email,
+                stream_name,
+                content=content
+            )
+        self.assertEqual(m.call_count, 1)
+        users = m.call_args[0][1]
+        user_ids = {u['id'] for u in users}
+        return user_ids
+
     def test_unsub_mention(self):
         # type: () -> None
         cordelia = self.example_user('cordelia')
@@ -607,14 +620,15 @@ class StreamMessagesTest(ZulipTestCase):
         ).delete()
 
         def mention_cordelia():
-            # type: () -> None
+            # type: () -> Set[int]
             content = 'test @**Cordelia Lear** rules'
 
-            self.send_stream_message(
-                hamlet.email,
-                stream_name,
-                content=content,
+            user_ids = self._send_stream_message(
+                email=hamlet.email,
+                stream_name=stream_name,
+                content=content
             )
+            return user_ids
 
         def num_cordelia_messages():
             # type: () -> int
@@ -622,15 +636,16 @@ class StreamMessagesTest(ZulipTestCase):
                 user_profile=cordelia
             ).count()
 
-        mention_cordelia()
-
+        user_ids = mention_cordelia()
         self.assertEqual(0, num_cordelia_messages())
+        self.assertNotIn(cordelia.id, user_ids)
 
         # Make sure test isn't too brittle-subscribing
         # Cordelia and mentioning her should give her a
         # message.
         self.subscribe(cordelia, stream_name)
-        mention_cordelia()
+        user_ids = mention_cordelia()
+        self.assertIn(cordelia.id, user_ids)
         self.assertEqual(1, num_cordelia_messages())
 
     def test_message_bot_mentions(self):
@@ -655,12 +670,13 @@ class StreamMessagesTest(ZulipTestCase):
 
         content = 'test @**Normal Bot** rules'
 
-        self.send_stream_message(
-            hamlet.email,
-            stream_name,
+        user_ids = self._send_stream_message(
+            email=hamlet.email,
+            stream_name=stream_name,
             content=content
         )
 
+        self.assertIn(normal_bot.id, user_ids)
         user_message = most_recent_usermessage(normal_bot)
         self.assertEqual(user_message.message.content, content)
         self.assertTrue(user_message.flags.mentioned)