settings: Add email notifications for the followed topics.

This commit makes it possible for users to control
the email notifications for messages sent to followed topics
via a global notification setting.
Although there is no support for configuring this setting
through the UI yet.

Add five new fields to the UserBaseSettings class for
the "followed topic notifications" feature, similar to
stream notifications. But this commit consists only of
the implementation of email notifications.

api_docs/changelog.md

@@ -20,6 +20,13 @@ format used by the Zulip server that they are interacting with.
 
 ## Changes in Zulip 8.0
 
+**Feature level 189**
+
+* [`PATCH /realm/user_settings_defaults`](/api/update-realm-user-settings-defaults),
+  [`POST /register`](/api/register-queue), [`PATCH /settings`](/api/update-settings):
+  Added `enable_followed_topic_email_notifications` field to control
+  email notifications for messages sent to followed topics.
+
 **Feature level 188**
 
 * [`POST /users/me/muted_users/{muted_user_id}`](/api/mute-user),

templates/zerver/emails/missed_message.html

@@ -33,6 +33,8 @@
     {% trans %}You are receiving this because everyone was mentioned in #{{ stream_name }}.{% endtrans %}<br />
     {% elif stream_email_notify %}
     {% trans %}You are receiving this because you have email notifications enabled for #{{ stream_name }}.{% endtrans %}<br />
+    {% elif followed_topic_email_notify %}
+    {% trans %}You are receiving this because you have email notifications enabled for topics you follow.{% endtrans %}<br />
     {% endif %}
     {% if reply_to_zulip %}
     {% trans notif_url=realm_uri + "/#settings/notifications" %}Reply to this email directly, <a href="{{ narrow_url }}">view it in {{ realm_name }} Zulip</a>, or <a href="{{ notif_url }}">manage email preferences</a>.{% endtrans %}

templates/zerver/emails/missed_message.subject.txt

@@ -1,7 +1,7 @@
 {% if show_message_content %}
     {% if group_pm %} {% trans %}Group DMs with {{ huddle_display_name }}{% endtrans %}
     {% elif private_message %} {% trans %}DMs with {{ sender_str }}{% endtrans %}
-    {% elif stream_email_notify or mention %}
+    {% elif stream_email_notify or mention or followed_topic_email_notify %}
         {#
         Some email clients, like Gmail Web (as of 2022), will auto-thread
         emails that share a subject and recipients, but will disregard

templates/zerver/emails/missed_message.txt

@@ -29,6 +29,8 @@ See {{ alert_notif_url }} for more details.
 {% trans %}You are receiving this because everyone was mentioned in #{{ stream_name }}.{% endtrans %}
 {% elif stream_email_notify %}
 {% trans %}You are receiving this because you have email notifications enabled for #{{ stream_name }}.{% endtrans %}
+{% elif followed_topic_email_notify %}
+{% trans %}You are receiving this because you have email notifications enabled for topics you follow.{% endtrans %}
 {% endif %}
 
 {% if reply_to_zulip  %}

zerver/actions/message_edit.py

@@ -473,6 +473,7 @@ def do_update_message(
         event["pm_mention_email_disabled_user_ids"] = list(info.pm_mention_email_disabled_user_ids)
         event["stream_push_user_ids"] = list(info.stream_push_user_ids)
         event["stream_email_user_ids"] = list(info.stream_email_user_ids)
+        event["followed_topic_email_user_ids"] = list(info.followed_topic_email_user_ids)
         event["muted_sender_user_ids"] = list(info.muted_sender_user_ids)
         event["prior_mention_user_ids"] = list(prior_mention_user_ids)
         event["presence_idle_user_ids"] = filter_presence_idle_user_ids(info.active_user_ids)

zerver/actions/message_send.py

@@ -166,6 +166,7 @@ class RecipientInfoResult:
     stream_email_user_ids: Set[int]
     stream_push_user_ids: Set[int]
     wildcard_mention_user_ids: Set[int]
+    followed_topic_email_user_ids: Set[int]
     muted_sender_user_ids: Set[int]
     um_eligible_user_ids: Set[int]
     long_term_idle_user_ids: Set[int]
@@ -196,6 +197,7 @@ def get_recipient_info(
     stream_push_user_ids: Set[int] = set()
     stream_email_user_ids: Set[int] = set()
     wildcard_mention_user_ids: Set[int] = set()
+    followed_topic_email_user_ids: Set[int] = set()
     muted_sender_user_ids: Set[int] = get_muting_users(sender_id)
 
     if recipient.type == Recipient.PERSONAL:
@@ -214,6 +216,7 @@ def get_recipient_info(
             get_subscriptions_for_send_message(
                 realm_id=realm_id,
                 stream_id=stream_topic.stream_id,
+                topic_name=stream_topic.topic_name,
                 possible_wildcard_mention=possible_wildcard_mention,
                 possibly_mentioned_user_ids=possibly_mentioned_user_ids,
             )
@@ -223,12 +226,16 @@ def get_recipient_info(
                 ),
                 user_profile_push_notifications=F("user_profile__enable_stream_push_notifications"),
                 user_profile_wildcard_mentions_notify=F("user_profile__wildcard_mentions_notify"),
+                followed_topic_email_notifications=F(
+                    "user_profile__enable_followed_topic_email_notifications"
+                ),
             )
             .values(
                 "user_profile_id",
                 "push_notifications",
                 "email_notifications",
                 "wildcard_mentions_notify",
+                "followed_topic_email_notifications",
                 "user_profile_email_notifications",
                 "user_profile_push_notifications",
                 "user_profile_wildcard_mentions_notify",
@@ -257,6 +264,21 @@ def get_recipient_info(
         stream_push_user_ids = notification_recipients("push_notifications")
         stream_email_user_ids = notification_recipients("email_notifications")
 
+        def followed_topic_notification_recipients(setting: str) -> Set[int]:
+            return {
+                row["user_profile_id"]
+                for row in subscription_rows
+                if user_id_to_visibility_policy.get(
+                    row["user_profile_id"], UserTopic.VisibilityPolicy.INHERIT
+                )
+                == UserTopic.VisibilityPolicy.FOLLOWED
+                and row["followed_topic_" + setting]
+            }
+
+        followed_topic_email_user_ids = followed_topic_notification_recipients(
+            "email_notifications"
+        )
+
         if possible_wildcard_mention:
             # We calculate `wildcard_mention_user_ids` only if there's a possible
             # wildcard mention in the message. This is important so as to avoid
@@ -381,6 +403,7 @@ def get_recipient_info(
         stream_push_user_ids=stream_push_user_ids,
         stream_email_user_ids=stream_email_user_ids,
         wildcard_mention_user_ids=wildcard_mention_user_ids,
+        followed_topic_email_user_ids=followed_topic_email_user_ids,
         muted_sender_user_ids=muted_sender_user_ids,
         um_eligible_user_ids=um_eligible_user_ids,
         long_term_idle_user_ids=long_term_idle_user_ids,
@@ -564,6 +587,7 @@ def build_message_send_dict(
         pm_mention_push_disabled_user_ids=info.pm_mention_push_disabled_user_ids,
         stream_push_user_ids=info.stream_push_user_ids,
         stream_email_user_ids=info.stream_email_user_ids,
+        followed_topic_email_user_ids=info.followed_topic_email_user_ids,
         muted_sender_user_ids=info.muted_sender_user_ids,
         um_eligible_user_ids=info.um_eligible_user_ids,
         long_term_idle_user_ids=info.long_term_idle_user_ids,
@@ -588,6 +612,7 @@ def create_user_messages(
     stream_push_user_ids: AbstractSet[int],
     stream_email_user_ids: AbstractSet[int],
     mentioned_user_ids: AbstractSet[int],
+    followed_topic_email_user_ids: AbstractSet[int],
     mark_as_read_user_ids: Set[int],
     limit_unread_user_ids: Optional[Set[int]],
     scheduled_message_to_self: bool,
@@ -648,6 +673,7 @@ def create_user_messages(
             user_profile_id in long_term_idle_user_ids
             and user_profile_id not in stream_push_user_ids
             and user_profile_id not in stream_email_user_ids
+            and user_profile_id not in followed_topic_email_user_ids
             and is_stream_message
             and int(flags) == 0
         ):
@@ -761,6 +787,7 @@ def do_send_messages(
                 stream_push_user_ids=send_request.stream_push_user_ids,
                 stream_email_user_ids=send_request.stream_email_user_ids,
                 mentioned_user_ids=mentioned_user_ids,
+                followed_topic_email_user_ids=send_request.followed_topic_email_user_ids,
                 mark_as_read_user_ids=mark_as_read_user_ids,
                 limit_unread_user_ids=send_request.limit_unread_user_ids,
                 scheduled_message_to_self=scheduled_message_to_self,
@@ -861,6 +888,7 @@ def do_send_messages(
                 stream_push_user_ids=send_request.stream_push_user_ids,
                 stream_email_user_ids=send_request.stream_email_user_ids,
                 wildcard_mention_user_ids=send_request.wildcard_mention_user_ids,
+                followed_topic_email_user_ids=send_request.followed_topic_email_user_ids,
                 muted_sender_user_ids=send_request.muted_sender_user_ids,
                 all_bot_user_ids=send_request.all_bot_user_ids,
             )
@@ -886,6 +914,7 @@ def do_send_messages(
             stream_push_user_ids=list(send_request.stream_push_user_ids),
             stream_email_user_ids=list(send_request.stream_email_user_ids),
             wildcard_mention_user_ids=list(send_request.wildcard_mention_user_ids),
+            followed_topic_email_user_ids=list(send_request.followed_topic_email_user_ids),
             muted_sender_user_ids=list(send_request.muted_sender_user_ids),
             all_bot_user_ids=list(send_request.all_bot_user_ids),
             disable_external_notifications=send_request.disable_external_notifications,

zerver/lib/email_notifications.py

@@ -457,6 +457,7 @@ def do_send_missedmessage_events_reply_in_zulip(
         personal_mentioned=personal_mentioned,
         wildcard_mentioned="wildcard_mentioned" in unique_triggers,
         stream_email_notify="stream_email_notify" in unique_triggers,
+        followed_topic_email_notify="followed_topic_email_notify" in unique_triggers,
         mention_count=triggers.count("mentioned") + triggers.count("wildcard_mentioned"),
         mentioned_user_group_name=mentioned_user_group_name,
     )
@@ -508,7 +509,11 @@ def do_send_missedmessage_events_reply_in_zulip(
             context.update(huddle_display_name=huddle_display_name)
     elif missed_messages[0]["message"].recipient.type == Recipient.PERSONAL:
         context.update(private_message=True)
-    elif context["mention"] or context["stream_email_notify"]:
+    elif (
+        context["mention"]
+        or context["stream_email_notify"]
+        or context["followed_topic_email_notify"]
+    ):
         # Keep only the senders who actually mentioned the user
         if context["mention"]:
             senders = list(

zerver/lib/message.py

@@ -156,6 +156,8 @@ class SendMessageRequest:
     pm_mention_email_disabled_user_ids: Set[int]
     stream_push_user_ids: Set[int]
     stream_email_user_ids: Set[int]
+    # IDs of users who have followed the topic the message is being sent to, and have the followed topic email notifications setting ON.
+    followed_topic_email_user_ids: Set[int]
     muted_sender_user_ids: Set[int]
     um_eligible_user_ids: Set[int]
     long_term_idle_user_ids: Set[int]

zerver/lib/notification_data.py

@@ -19,15 +19,20 @@ class UserMessageNotificationsData:
     wildcard_mention_push_notify: bool
     stream_push_notify: bool
     stream_email_notify: bool
+    followed_topic_email_notify: bool
     sender_is_muted: bool
     disable_external_notifications: bool
 
     def __post_init__(self) -> None:
         # Check that there's no dubious data.
         if self.pm_email_notify or self.pm_push_notify:
-            assert not (self.stream_email_notify or self.stream_push_notify)
+            assert not (
+                self.stream_email_notify
+                or self.stream_push_notify
+                or self.followed_topic_email_notify
+            )
 
-        if self.stream_email_notify or self.stream_push_notify:
+        if self.stream_email_notify or self.stream_push_notify or self.followed_topic_email_notify:
             assert not (self.pm_email_notify or self.pm_push_notify)
 
     @classmethod
@@ -44,6 +49,7 @@ class UserMessageNotificationsData:
         stream_push_user_ids: Set[int],
         stream_email_user_ids: Set[int],
         wildcard_mention_user_ids: Set[int],
+        followed_topic_email_user_ids: Set[int],
         muted_sender_user_ids: Set[int],
         all_bot_user_ids: Set[int],
     ) -> "UserMessageNotificationsData":
@@ -60,6 +66,7 @@ class UserMessageNotificationsData:
                 online_push_enabled=False,
                 stream_push_notify=False,
                 stream_email_notify=False,
+                followed_topic_email_notify=False,
                 sender_is_muted=False,
                 disable_external_notifications=False,
             )
@@ -97,6 +104,7 @@ class UserMessageNotificationsData:
             online_push_enabled=(user_id in online_push_user_ids),
             stream_push_notify=(user_id in stream_push_user_ids),
             stream_email_notify=(user_id in stream_email_user_ids),
+            followed_topic_email_notify=(user_id in followed_topic_email_user_ids),
             sender_is_muted=(user_id in muted_sender_user_ids),
             disable_external_notifications=disable_external_notifications,
         )
@@ -168,6 +176,8 @@ class UserMessageNotificationsData:
             return NotificationTriggers.MENTION
         elif self.wildcard_mention_email_notify:
             return NotificationTriggers.WILDCARD_MENTION
+        elif self.followed_topic_email_notify:
+            return NotificationTriggers.FOLLOWED_TOPIC_EMAIL
         elif self.stream_email_notify:
             return NotificationTriggers.STREAM_EMAIL
         else:

zerver/lib/stream_subscription.py

@@ -7,7 +7,7 @@ from typing import AbstractSet, Any, Collection, Dict, List, Optional, Set
 from django.db.models import Q, QuerySet
 from django_stubs_ext import ValuesQuerySet
 
-from zerver.models import AlertWord, Realm, Recipient, Stream, Subscription, UserProfile
+from zerver.models import AlertWord, Realm, Recipient, Stream, Subscription, UserProfile, UserTopic
 
 
 @dataclass
@@ -305,6 +305,7 @@ def get_subscriptions_for_send_message(
     *,
     realm_id: int,
     stream_id: int,
+    topic_name: str,
     possible_wildcard_mention: bool,
     possibly_mentioned_user_ids: AbstractSet[int],
 ) -> QuerySet[Subscription]:
@@ -356,5 +357,12 @@ def get_subscriptions_for_send_message(
                 "user_profile_id"
             )
         )
+        | Q(
+            user_profile_id__in=UserTopic.objects.filter(
+                stream_id=stream_id,
+                topic_name__iexact=topic_name,
+                visibility_policy=UserTopic.VisibilityPolicy.FOLLOWED,
+            ).values_list("user_profile_id")
+        )
     )
     return query

zerver/lib/test_classes.py

@@ -1729,6 +1729,7 @@ Output:
             wildcard_mention_push_notify=kwargs.get("wildcard_mention_push_notify", False),
             stream_email_notify=kwargs.get("stream_email_notify", False),
             stream_push_notify=kwargs.get("stream_push_notify", False),
+            followed_topic_email_notify=kwargs.get("followed_topic_email_notify", False),
             sender_is_muted=kwargs.get("sender_is_muted", False),
             disable_external_notifications=kwargs.get("disable_external_notifications", False),
         )

zerver/migrations/0331_scheduledmessagenotificationemail.py

@@ -28,6 +28,7 @@ class Migration(migrations.Migration):
                             ("mentioned", "Mention"),
                             ("wildcard_mentioned", "Wildcard mention"),
                             ("stream_email_notify", "Stream notifications enabled"),
+                            ("followed_topic_email_notify", "Followed topic notifications enabled"),
                         ]
                     ),
                 ),

zerver/migrations/0453_followed_topic_notifications.py

@@ -0,0 +1,62 @@
+# Generated by Django 4.2.1 on 2023-05-24 11:09
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+    dependencies = [
+        ("zerver", "0452_realmauditlog_extra_data_json"),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name="realmuserdefault",
+            name="enable_followed_topic_audible_notifications",
+            field=models.BooleanField(default=True),
+        ),
+        migrations.AddField(
+            model_name="realmuserdefault",
+            name="enable_followed_topic_desktop_notifications",
+            field=models.BooleanField(default=True),
+        ),
+        migrations.AddField(
+            model_name="realmuserdefault",
+            name="enable_followed_topic_email_notifications",
+            field=models.BooleanField(default=True),
+        ),
+        migrations.AddField(
+            model_name="realmuserdefault",
+            name="enable_followed_topic_push_notifications",
+            field=models.BooleanField(default=True),
+        ),
+        migrations.AddField(
+            model_name="realmuserdefault",
+            name="enable_followed_topic_wildcard_mentions_notify",
+            field=models.BooleanField(default=True),
+        ),
+        migrations.AddField(
+            model_name="userprofile",
+            name="enable_followed_topic_audible_notifications",
+            field=models.BooleanField(default=True),
+        ),
+        migrations.AddField(
+            model_name="userprofile",
+            name="enable_followed_topic_desktop_notifications",
+            field=models.BooleanField(default=True),
+        ),
+        migrations.AddField(
+            model_name="userprofile",
+            name="enable_followed_topic_email_notifications",
+            field=models.BooleanField(default=True),
+        ),
+        migrations.AddField(
+            model_name="userprofile",
+            name="enable_followed_topic_push_notifications",
+            field=models.BooleanField(default=True),
+        ),
+        migrations.AddField(
+            model_name="userprofile",
+            name="enable_followed_topic_wildcard_mentions_notify",
+            field=models.BooleanField(default=True),
+        ),
+    ]

zerver/models.py

@@ -1589,6 +1589,13 @@ class UserBaseSettings(models.Model):
     notification_sound = models.CharField(max_length=20, default="zulip")
     wildcard_mentions_notify = models.BooleanField(default=True)
 
+    # Followed Topics notifications.
+    enable_followed_topic_desktop_notifications = models.BooleanField(default=True)
+    enable_followed_topic_email_notifications = models.BooleanField(default=True)
+    enable_followed_topic_push_notifications = models.BooleanField(default=True)
+    enable_followed_topic_audible_notifications = models.BooleanField(default=True)
+    enable_followed_topic_wildcard_mentions_notify = models.BooleanField(default=True)
+
     # PM + @-mention notifications.
     enable_desktop_notifications = models.BooleanField(default=True)
     pm_content_in_desktop_notifications = models.BooleanField(default=True)
@@ -1716,6 +1723,7 @@ class UserBaseSettings(models.Model):
 
     modern_notification_settings: Dict[str, Any] = dict(
         # Add new notification settings here.
+        enable_followed_topic_email_notifications=bool,
     )
 
     notification_setting_types = {
@@ -4276,6 +4284,7 @@ class NotificationTriggers:
     WILDCARD_MENTION = "wildcard_mentioned"
     STREAM_PUSH = "stream_push_notify"
     STREAM_EMAIL = "stream_email_notify"
+    FOLLOWED_TOPIC_EMAIL = "followed_topic_email_notify"
 
 
 class ScheduledMessageNotificationEmail(models.Model):
@@ -4293,6 +4302,7 @@ class ScheduledMessageNotificationEmail(models.Model):
         (NotificationTriggers.MENTION, "Mention"),
         (NotificationTriggers.WILDCARD_MENTION, "Wildcard mention"),
         (NotificationTriggers.STREAM_EMAIL, "Stream notifications enabled"),
+        (NotificationTriggers.FOLLOWED_TOPIC_EMAIL, "Followed topic notifications enabled"),
     ]
 
     trigger = models.TextField(choices=EMAIL_NOTIFICATION_TRIGGER_CHOICES)

zerver/openapi/zulip.yaml

@@ -9748,6 +9748,15 @@ paths:
           schema:
             type: boolean
           example: true
+        - name: enable_followed_topic_email_notifications
+          in: query
+          description: |
+            Enable email notifications for messages sent to followed topics.
+
+            **Changes**: New in Zulip 8.0 (feature level 189).
+          schema:
+            type: boolean
+          example: true
         - name: email_notifications_batching_period_seconds
           in: query
           description: |
@@ -11840,6 +11849,12 @@ paths:
                             description: |
                               Enable audible desktop notifications for private messages and
                               @-mentions.
+                          enable_followed_topic_email_notifications:
+                            type: boolean
+                            description: |
+                              Enable email notifications for messages sent to followed topics.
+
+                              **Changes**: New in Zulip 8.0 (feature level 189).
                           email_notifications_batching_period_seconds:
                             type: integer
                             description: |
@@ -13900,6 +13915,12 @@ paths:
                             description: |
                               Enable mobile notification for private messages and @-mentions received
                               when the user is online.
+                          enable_followed_topic_email_notifications:
+                            type: boolean
+                            description: |
+                              Enable email notifications for messages sent to followed topics.
+
+                              **Changes**: New in Zulip 8.0 (feature level 189).
                           enable_digest_emails:
                             type: boolean
                             description: |
@@ -15033,6 +15054,15 @@ paths:
           schema:
             type: boolean
           example: true
+        - name: enable_followed_topic_email_notifications
+          in: query
+          description: |
+            Enable email notifications for messages sent to followed topics.
+
+            **Changes**: New in Zulip 8.0 (feature level 189).
+          schema:
+            type: boolean
+          example: true
         - name: enable_digest_emails
           in: query
           description: |

zerver/tests/test_email_notifications.py

@@ -1851,6 +1851,26 @@ class TestMissedMessages(ZulipTestCase):
                 ],
             )
 
+    def test_followed_topic_missed_message(self) -> None:
+        hamlet = self.example_user("hamlet")
+        othello = self.example_user("othello")
+        msg_id = self.send_stream_message(othello, "Denmark")
+
+        handle_missedmessage_emails(
+            hamlet.id,
+            [
+                {"message_id": msg_id, "trigger": "followed_topic_email_notify"},
+            ],
+        )
+        self.assert_length(mail.outbox, 1)
+        email_subject = mail.outbox[0].subject
+        email_body = mail.outbox[0].body
+        self.assertEqual("#Denmark > test", email_subject)
+        self.assertIn(
+            "You are receiving this because you have email notifications enabled for topics you follow.",
+            email_body,
+        )
+
 
 class TestFollowupEmailDelay(ZulipTestCase):
     def test_get_onboarding_email_schedule(self) -> None:

zerver/tests/test_event_queue.py

@@ -760,6 +760,56 @@ class MissedMessageHookTest(ZulipTestCase):
                 already_notified={"email_notified": False, "push_notified": False},
             )
 
+    def test_followed_topic_email_notify(self) -> None:
+        # By default, messages sent in followed topics should send email notifications.
+        do_set_user_topic_visibility_policy(
+            self.user_profile,
+            get_stream("Denmark", self.user_profile.realm),
+            "followed_topic_test",
+            visibility_policy=UserTopic.VisibilityPolicy.FOLLOWED,
+        )
+        msg_id = self.send_stream_message(
+            self.iago, "Denmark", content="what's up everyone?", topic_name="followed_topic_test"
+        )
+        with mock.patch("zerver.tornado.event_queue.maybe_enqueue_notifications") as mock_enqueue:
+            missedmessage_hook(self.user_profile.id, self.client_descriptor, True)
+            mock_enqueue.assert_called_once()
+            args_dict = mock_enqueue.call_args_list[0][1]
+
+            self.assert_maybe_enqueue_notifications_call_args(
+                args_dict=args_dict,
+                message_id=msg_id,
+                user_id=self.user_profile.id,
+                followed_topic_email_notify=True,
+                already_notified={"email_notified": True, "push_notified": False},
+            )
+
+    def test_followed_topic_email_notify_global_setting(self) -> None:
+        do_change_user_setting(
+            self.user_profile, "enable_followed_topic_email_notifications", False, acting_user=None
+        )
+        do_set_user_topic_visibility_policy(
+            self.user_profile,
+            get_stream("Denmark", self.user_profile.realm),
+            "followed_topic_test",
+            visibility_policy=UserTopic.VisibilityPolicy.FOLLOWED,
+        )
+        msg_id = self.send_stream_message(
+            self.iago, "Denmark", content="what's up everyone?", topic_name="followed_topic_test"
+        )
+        with mock.patch("zerver.tornado.event_queue.maybe_enqueue_notifications") as mock_enqueue:
+            missedmessage_hook(self.user_profile.id, self.client_descriptor, True)
+            mock_enqueue.assert_called_once()
+            args_dict = mock_enqueue.call_args_list[0][1]
+
+            self.assert_maybe_enqueue_notifications_call_args(
+                args_dict=args_dict,
+                message_id=msg_id,
+                user_id=self.user_profile.id,
+                followed_topic_email_notify=False,
+                already_notified={"email_notified": False, "push_notified": False},
+            )
+
     def test_muted_sender(self) -> None:
         do_mute_user(self.user_profile, self.iago)
         msg_id = self.send_personal_message(self.iago, self.user_profile)

zerver/tests/test_events.py

@@ -1946,6 +1946,17 @@ class NormalActionsTest(BaseAction):
                 self.user_profile, notification_setting, False, acting_user=self.user_profile
             )
 
+            num_events = 2
+            is_modern_notification_setting = (
+                notification_setting in self.user_profile.modern_notification_settings
+            )
+            if is_modern_notification_setting:
+                # The legacy event format is not sent for modern_notification_settings
+                # as it exists only for backwards-compatibility with
+                # clients that don't support the new user_settings event type.
+                # We only send the legacy event for settings added before Feature level 89.
+                num_events = 1
+
             for setting_value in [True, False]:
                 events = self.verify_action(
                     lambda: do_change_user_setting(
@@ -1954,10 +1965,11 @@ class NormalActionsTest(BaseAction):
                         setting_value,
                         acting_user=self.user_profile,
                     ),
-                    num_events=2,
+                    num_events=num_events,
                 )
                 check_user_settings_update("events[0]", events[0])
-                check_update_global_notifications("events[1]", events[1], setting_value)
+                if not is_modern_notification_setting:
+                    check_update_global_notifications("events[1]", events[1], setting_value)
 
                 # Also test with notification_settings_null=True
                 events = self.verify_action(
@@ -1969,10 +1981,11 @@ class NormalActionsTest(BaseAction):
                     ),
                     notification_settings_null=True,
                     state_change_expected=False,
-                    num_events=2,
+                    num_events=num_events,
                 )
                 check_user_settings_update("events[0]", events[0])
-                check_update_global_notifications("events[1]", events[1], setting_value)
+                if not is_modern_notification_setting:
+                    check_update_global_notifications("events[1]", events[1], setting_value)
 
     def test_change_presence_enabled(self) -> None:
         presence_enabled_setting = "presence_enabled"

zerver/tests/test_notification_data.py

@@ -182,6 +182,16 @@ class TestNotificationData(ZulipTestCase):
         )
         self.assertTrue(user_data.is_email_notifiable(acting_user_id=acting_user_id, idle=True))
 
+        # Followed Topic notification
+        user_data = self.create_user_notifications_data_object(
+            user_id=user_id, followed_topic_email_notify=True
+        )
+        self.assertEqual(
+            user_data.get_email_notification_trigger(acting_user_id=acting_user_id, idle=True),
+            "followed_topic_email_notify",
+        )
+        self.assertTrue(user_data.is_email_notifiable(acting_user_id=acting_user_id, idle=True))
+
         # Test no notifications when not idle
         user_data = self.create_user_notifications_data_object(
             user_id=user_id, pm_email_notify=True
@@ -267,6 +277,7 @@ class TestNotificationData(ZulipTestCase):
                 stream_email_user_ids=set(),
                 stream_push_user_ids=set(),
                 wildcard_mention_user_ids=set(),
+                followed_topic_email_user_ids=set(),
             )
             self.assertEqual(user_data.is_notifiable(acting_user_id=1000, idle=True), notifiable)
 

zerver/tests/test_soft_deactivation.py

@@ -631,6 +631,7 @@ class SoftDeactivationMessageTest(ZulipTestCase):
                     get_subscriptions_for_send_message(
                         realm_id=realm_id,
                         stream_id=stream_id,
+                        topic_name=topic_name,
                         possible_wildcard_mention=possible_wildcard_mention,
                         possibly_mentioned_user_ids=possibly_mentioned_user_ids,
                     )

zerver/tests/test_users.py

@@ -1763,6 +1763,7 @@ class RecipientInfoTest(ZulipTestCase):
             stream_push_user_ids=set(),
             stream_email_user_ids=set(),
             wildcard_mention_user_ids=set(),
+            followed_topic_email_user_ids=set(),
             muted_sender_user_ids=set(),
             um_eligible_user_ids=all_user_ids,
             long_term_idle_user_ids=set(),
@@ -1979,6 +1980,39 @@ class RecipientInfoTest(ZulipTestCase):
         self.assertEqual(info.default_bot_user_ids, {normal_bot.id})
         self.assertEqual(info.all_bot_user_ids, {normal_bot.id, service_bot.id})
 
+        # Now Hamlet follows the topic with the 'followed_topic_email_notifications'
+        # global setting enabled by default.
+        do_set_user_topic_visibility_policy(
+            hamlet,
+            stream,
+            topic_name,
+            visibility_policy=UserTopic.VisibilityPolicy.FOLLOWED,
+        )
+
+        info = get_recipient_info(
+            realm_id=realm.id,
+            recipient=recipient,
+            sender_id=hamlet.id,
+            stream_topic=stream_topic,
+        )
+        self.assertEqual(info.followed_topic_email_user_ids, {hamlet.id})
+
+        # Omit Hamlet from followed_topic_email_user_ids
+        do_change_user_setting(
+            hamlet,
+            "enable_followed_topic_email_notifications",
+            False,
+            acting_user=None,
+        )
+
+        info = get_recipient_info(
+            realm_id=realm.id,
+            recipient=recipient,
+            sender_id=hamlet.id,
+            stream_topic=stream_topic,
+        )
+        self.assertEqual(info.followed_topic_email_user_ids, set())
+
     def test_get_recipient_info_invalid_recipient_type(self) -> None:
         hamlet = self.example_user("hamlet")
         realm = hamlet.realm

zerver/tornado/event_queue.py

@@ -780,6 +780,7 @@ def missedmessage_hook(
             wildcard_mention_email_notify=internal_data.get("wildcard_mention_email_notify", False),
             stream_push_notify=internal_data.get("stream_push_notify", False),
             stream_email_notify=internal_data.get("stream_email_notify", False),
+            followed_topic_email_notify=internal_data.get("followed_topic_email_notify", False),
             # Since one is by definition idle, we don't need to check online_push_enabled
             online_push_enabled=False,
             disable_external_notifications=internal_data.get(
@@ -933,6 +934,7 @@ def process_message_event(
     stream_push_user_ids = set(event_template.get("stream_push_user_ids", []))
     stream_email_user_ids = set(event_template.get("stream_email_user_ids", []))
     wildcard_mention_user_ids = set(event_template.get("wildcard_mention_user_ids", []))
+    followed_topic_email_user_ids = set(event_template.get("followed_topic_email_user_ids", []))
     muted_sender_user_ids = set(event_template.get("muted_sender_user_ids", []))
     all_bot_user_ids = set(event_template.get("all_bot_user_ids", []))
     disable_external_notifications = event_template.get("disable_external_notifications", False)
@@ -983,6 +985,7 @@ def process_message_event(
             stream_push_user_ids=stream_push_user_ids,
             stream_email_user_ids=stream_email_user_ids,
             wildcard_mention_user_ids=wildcard_mention_user_ids,
+            followed_topic_email_user_ids=followed_topic_email_user_ids,
             muted_sender_user_ids=muted_sender_user_ids,
             all_bot_user_ids=all_bot_user_ids,
         )
@@ -1134,6 +1137,7 @@ def process_message_update_event(
     stream_push_user_ids = set(event_template.pop("stream_push_user_ids", []))
     stream_email_user_ids = set(event_template.pop("stream_email_user_ids", []))
     wildcard_mention_user_ids = set(event_template.pop("wildcard_mention_user_ids", []))
+    followed_topic_email_user_ids = set(event_template.pop("followed_topic_email_user_ids", []))
     muted_sender_user_ids = set(event_template.pop("muted_sender_user_ids", []))
     all_bot_user_ids = set(event_template.pop("all_bot_user_ids", []))
     disable_external_notifications = event_template.pop("disable_external_notifications", False)
@@ -1194,6 +1198,7 @@ def process_message_update_event(
                 stream_push_user_ids=stream_push_user_ids,
                 stream_email_user_ids=stream_email_user_ids,
                 wildcard_mention_user_ids=wildcard_mention_user_ids,
+                followed_topic_email_user_ids=followed_topic_email_user_ids,
                 muted_sender_user_ids=muted_sender_user_ids,
                 all_bot_user_ids=all_bot_user_ids,
             )
@@ -1266,7 +1271,11 @@ def maybe_enqueue_notifications_for_message_update(
         # without extending the UserMessage data model.
         return
 
-    if user_notifications_data.stream_push_notify or user_notifications_data.stream_email_notify:
+    if (
+        user_notifications_data.stream_push_notify
+        or user_notifications_data.stream_email_notify
+        or user_notifications_data.followed_topic_email_notify
+    ):
         # Currently we assume that if this flag is set to True, then
         # the user already was notified about the earlier message,
         # so we short circuit.  We may handle this more rigorously

zerver/views/realm.py

@@ -426,6 +426,9 @@ def update_realm_user_settings_defaults(
         json_validator=check_bool, default=None
     ),
     wildcard_mentions_notify: Optional[bool] = REQ(json_validator=check_bool, default=None),
+    enable_followed_topic_email_notifications: Optional[bool] = REQ(
+        json_validator=check_bool, default=None
+    ),
     notification_sound: Optional[str] = REQ(default=None),
     enable_desktop_notifications: Optional[bool] = REQ(json_validator=check_bool, default=None),
     enable_sounds: Optional[bool] = REQ(json_validator=check_bool, default=None),

zerver/views/user_settings.py

@@ -193,6 +193,9 @@ def json_change_settings(
         json_validator=check_bool, default=None
     ),
     wildcard_mentions_notify: Optional[bool] = REQ(json_validator=check_bool, default=None),
+    enable_followed_topic_email_notifications: Optional[bool] = REQ(
+        json_validator=check_bool, default=None
+    ),
     notification_sound: Optional[str] = REQ(default=None),
     enable_desktop_notifications: Optional[bool] = REQ(json_validator=check_bool, default=None),
     enable_sounds: Optional[bool] = REQ(json_validator=check_bool, default=None),