diff --git a/app/services/post_alerter.rb b/app/services/post_alerter.rb
index da681499fb0..8568d5fc5a5 100644
--- a/app/services/post_alerter.rb
+++ b/app/services/post_alerter.rb
@@ -802,7 +802,12 @@ class PostAlerter
      LEFT JOIN tag_group_memberships tgm ON tag_users.tag_id = tgm.tag_id
      LEFT JOIN tag_group_permissions tgp ON tgm.tag_group_id = tgp.tag_group_id
      LEFT JOIN group_users gu ON gu.user_id = tag_users.user_id
-         WHERE (tgp.group_id IS NULL OR tgp.group_id = gu.group_id OR gu.group_id = :staff_group_id)
+         WHERE (
+            tgp.group_id IS NULL OR
+            tgp.group_id = gu.group_id OR
+            tgp.group_id = :everyone_group_id OR
+            gu.group_id = :staff_group_id
+          )
                AND (tag_users.notification_level = :watching
                     AND tag_users.tag_id IN (:tag_ids)
                     AND (tu.user_id IS NULL OR tu.notification_level = :watching))
@@ -814,7 +819,8 @@ class PostAlerter
       topic_id: post.topic_id,
       category_id: post.topic.category_id,
       tag_ids: tag_ids,
-      staff_group_id: Group::AUTO_GROUPS[:staff]
+      staff_group_id: Group::AUTO_GROUPS[:staff],
+      everyone_group_id: Group::AUTO_GROUPS[:everyone]
     )
 
     if group_ids.present?
diff --git a/spec/models/tag_user_spec.rb b/spec/models/tag_user_spec.rb
index 36dc462053e..96af3d950ff 100644
--- a/spec/models/tag_user_spec.rb
+++ b/spec/models/tag_user_spec.rb
@@ -183,6 +183,11 @@ describe TagUser do
 
       it "sets notification levels correctly" do
 
+        # define a wide open tag group to ensure it also works
+        group = TagGroup.new(name: 'Visible & usable by everyone', tag_names: [watched_tag.name])
+        group.permissions = [[Group::AUTO_GROUPS[:everyone], TagGroupPermission.permission_types[:full]]]
+        group.save!
+
         expect(Notification.where(user_id: user.id, topic_id: watched_post.topic_id).count).to eq 1
         expect(Notification.where(user_id: user.id, topic_id: tracked_post.topic_id).count).to eq 0
 
diff --git a/spec/services/post_alerter_spec.rb b/spec/services/post_alerter_spec.rb
index ddc26a448be..b842424438e 100644
--- a/spec/services/post_alerter_spec.rb
+++ b/spec/services/post_alerter_spec.rb
@@ -1372,8 +1372,10 @@ describe PostAlerter do
         tag = Fabricate(:tag)
         topic = Fabricate(:topic, tags: [tag])
         post = Fabricate(:post, topic: topic)
-        tag_group = Fabricate(:tag_group, tags: [tag])
-        Fabricate(:tag_group_permission, tag_group: tag_group, group: group)
+
+        tag_group = TagGroup.new(name: 'Only visible to group', tag_names: [tag.name])
+        tag_group.permissions = [[group.id, TagGroupPermission.permission_types[:full]]]
+        tag_group.save!
 
         TagUser.change(user.id, tag.id, TagUser.notification_levels[:watching])