diff --git a/wagtail/admin/tests/pages/test_edit_page.py b/wagtail/admin/tests/pages/test_edit_page.py
index 7eab6481da..2d3e00cace 100644
--- a/wagtail/admin/tests/pages/test_edit_page.py
+++ b/wagtail/admin/tests/pages/test_edit_page.py
@@ -2100,6 +2100,7 @@ class TestCommenting(TestCase, WagtailTestUtils):
         self.subscriber = self.create_user('subscriber')
         self.non_subscriber = self.create_user('non-subscriber')
         self.non_subscriber_2 = self.create_user('non-subscriber-2')
+        self.never_emailed_user = self.create_user('never-emailed')
 
         PageSubscription.objects.create(
             page=self.child_page,
@@ -2113,6 +2114,23 @@ class TestCommenting(TestCase, WagtailTestUtils):
             comment_notifications=True
         )
 
+        # Add comment and reply on a different page for the never_emailed_user
+        # They should never be notified
+        comment_on_other_page = Comment.objects.create(
+            page=self.root_page,
+            user=self.never_emailed_user,
+            text='a comment'
+        )
+
+        CommentReply.objects.create(
+            user=self.never_emailed_user,
+            comment=comment_on_other_page,
+            text='a reply'
+        )
+
+    def assertNeverEmailedWrongUser(self):
+        self.assertNotIn(self.never_emailed_user.email, [to for email in mail.outbox for to in email.to])
+
     def test_new_comment(self):
         post_data = {
             'title': "I've been edited!",
@@ -2144,6 +2162,7 @@ class TestCommenting(TestCase, WagtailTestUtils):
 
         # Check notification email
         self.assertEqual(len(mail.outbox), 1)
+        self.assertNeverEmailedWrongUser()
         self.assertEqual(mail.outbox[0].to, [self.subscriber.email])
         self.assertEqual(mail.outbox[0].subject, 'test@email.com has updated comments on "I\'ve been edited! (simple page)"')
         self.assertIn('New comments:\n - "A test comment"\n\n', mail.outbox[0].body)
@@ -2283,6 +2302,7 @@ class TestCommenting(TestCase, WagtailTestUtils):
 
         # Check notification email
         self.assertEqual(len(mail.outbox), 2)
+        self.assertNeverEmailedWrongUser()
         # The non subscriber created the comment, so should also get an email
         self.assertEqual(mail.outbox[0].to, [self.non_subscriber.email])
         self.assertEqual(mail.outbox[0].subject, 'test@email.com has updated comments on "I\'ve been edited! (simple page)"')
@@ -2337,6 +2357,7 @@ class TestCommenting(TestCase, WagtailTestUtils):
 
         # Check notification email
         self.assertEqual(len(mail.outbox), 1)
+        self.assertNeverEmailedWrongUser()
         self.assertEqual(mail.outbox[0].to, [self.subscriber.email])
         self.assertEqual(mail.outbox[0].subject, 'test@email.com has updated comments on "I\'ve been edited! (simple page)"')
         self.assertIn('Deleted comments:\n - "A test comment"\n\n', mail.outbox[0].body)
@@ -2398,6 +2419,7 @@ class TestCommenting(TestCase, WagtailTestUtils):
 
         # Check notification email
         self.assertEqual(len(mail.outbox), 3)
+        self.assertNeverEmailedWrongUser()
 
         recipients = [mail.to for mail in mail.outbox]
         # The other non subscriber replied in the thread, so should get an email
diff --git a/wagtail/admin/views/pages/edit.py b/wagtail/admin/views/pages/edit.py
index 2edf11b450..9f942243f2 100644
--- a/wagtail/admin/views/pages/edit.py
+++ b/wagtail/admin/views/pages/edit.py
@@ -141,11 +141,11 @@ class EditView(TemplateResponseMixin, ContextMixin, HookResponseMixin, View):
         # Get subscribers to individual threads
         replies = CommentReply.objects.filter(comment_id__in=relevant_comment_ids)
         comments = Comment.objects.filter(id__in=relevant_comment_ids)
-        thread_users = get_user_model().objects.exclude(pk=self.request.user.pk).exclude(pk__in=subscribers.values_list('user_id', flat=True)).prefetch_related(
+        thread_users = get_user_model().objects.exclude(pk=self.request.user.pk).exclude(pk__in=subscribers.values_list('user_id', flat=True)).filter(
+            Q(comment_replies__comment_id__in=relevant_comment_ids) | Q(**{('%s__pk__in' % COMMENTS_RELATION_NAME): relevant_comment_ids})
+        ).prefetch_related(
             Prefetch('comment_replies', queryset=replies),
             Prefetch(COMMENTS_RELATION_NAME, queryset=comments)
-        ).exclude(
-            Q(comment_replies__isnull=True) & Q(**{('%s__isnull' % COMMENTS_RELATION_NAME): True})
         )
 
         # Skip if no recipients