new 'private_email_time_window_seconds' site setting

app/models/user_email_observer.rb

@@ -81,7 +81,7 @@ class UserEmailObserver < ActiveRecord::Observer
     end
 
     def private_delay
-      20.seconds
+      SiteSetting.private_email_time_window_seconds
     end
 
     def post_type

config/locales/server.en.yml

@@ -1038,6 +1038,7 @@ en:
     create_thumbnails: "Create thumbnails and lightbox images that are too large to fit in a post."
 
     email_time_window_mins: "Wait (n) minutes before sending any notification emails, to give users a chance to edit and finalize their posts."
+    private_email_time_window_seconds: "Wait (n) seconds before sending any private notification emails, to give users a chance to edit and finalize their posts."
     email_posts_context: "How many prior replies to include as context in notification emails."
     flush_timings_secs: "How frequently we flush timing data to the server, in seconds."
     title_max_word_length: "The maximum allowed word length, in characters, in a topic title."

config/site_settings.yml

@@ -496,6 +496,7 @@ email:
   email_time_window_mins:
     default: 10
     client: true
+  private_email_time_window_seconds: 20
   email_posts_context: 5
   digest_min_excerpt_length: 100
   digest_topics: 20

spec/models/user_email_observer_spec.rb

@@ -109,7 +109,7 @@ describe UserEmailObserver do
 
   context 'user_private_message' do
     let(:type) { :user_private_message }
-    let(:delay) { 20.seconds }
+    let(:delay) { SiteSetting.private_email_time_window_seconds }
     let!(:notification) { create_notification(6) }
 
     include_examples "enqueue_private"
@@ -124,7 +124,7 @@ describe UserEmailObserver do
 
   context 'user_invited_to_private_message' do
     let(:type) { :user_invited_to_private_message }
-    let(:delay) { 20.seconds }
+    let(:delay) { SiteSetting.private_email_time_window_seconds }
     let!(:notification) { create_notification(7) }
 
     include_examples "enqueue_public"
@@ -132,7 +132,7 @@ describe UserEmailObserver do
 
   context 'user_invited_to_topic' do
     let(:type) { :user_invited_to_topic }
-    let(:delay) { 20.seconds }
+    let(:delay) { SiteSetting.private_email_time_window_seconds }
     let!(:notification) { create_notification(13) }
 
     include_examples "enqueue_public"