PERF: Only log the first skipped email when user exceeds daily limit.

https://meta.discourse.org/t/cleaning-up-e-mail-logs/39132

app/jobs/regular/notify_mailing_list_subscribers.rb

@@ -80,13 +80,23 @@ module Jobs
     end
 
     def skip(to_address, user_id, post_id, reason_type)
-      SkippedEmailLog.create!(
+      attributes = {
         email_type: 'mailing_list',
         to_address: to_address,
         user_id: user_id,
         post_id: post_id,
         reason_type: reason_type
-      )
+      }
+
+      if reason_type == SkippedEmailLog.reason_types[:exceeded_emails_limit]
+        exists = SkippedEmailLog.exists?({
+          created_at: (Time.zone.now.beginning_of_day..Time.zone.now.end_of_day)
+        }.merge(attributes))
+
+        return if exists
+      end
+
+      SkippedEmailLog.create!(attributes)
     end
   end
 end

spec/jobs/notify_mailing_list_subscribers_spec.rb

@@ -126,8 +126,15 @@ describe Jobs::NotifyMailingListSubscribers do
             mailing_list_user.email_logs.create(email_type: 'foobar', to_address: mailing_list_user.email)
           }
 
-          Jobs::NotifyMailingListSubscribers.new.execute(post_id: post.id)
-          UserNotifications.expects(:mailing_list_notify).with(mailing_list_user, post).never
+          expect do
+            UserNotifications.expects(:mailing_list_notify)
+              .with(mailing_list_user, post)
+              .never
+
+            2.times do
+              Jobs::NotifyMailingListSubscribers.new.execute(post_id: post.id)
+            end
+          end.to change { SkippedEmailLog.count }.by(1)
 
           expect(SkippedEmailLog.exists?(
             email_type: "mailing_list",