diff --git a/app/mailers/protip_mailer.rb b/app/mailers/protip_mailer.rb
index a10bf4a3..b6abf4fb 100644
--- a/app/mailers/protip_mailer.rb
+++ b/app/mailers/protip_mailer.rb
@@ -16,7 +16,6 @@ class ProtipMailer < ActionMailer::Base
     endorsements: 'endorsements',
     protips_count: 'protips'
   }
-  ACTIVITY_SUBJECT_PREFIX = '[Coderwall]'
   CAMPAIGN_ID = 'protip_mailer-popular_protips'
 
   #################################################################################
diff --git a/app/workers/protip_mailer_popular_protips_worker.rb b/app/workers/protip_mailer_popular_protips_worker.rb
index cf9e520d..1795acf2 100644
--- a/app/workers/protip_mailer_popular_protips_worker.rb
+++ b/app/workers/protip_mailer_popular_protips_worker.rb
@@ -6,7 +6,17 @@ def perform(from, to)
     protips = ProtipMailer::Queries.popular_protips(from, to)
 
     User.find_each(batch_size: 100) do |user|
-      ProtipMailer.popular_protips(user, protips, from, to).deliver
+      begin
+        if REDIS.sismember(ProtipMailer::CAMPAIGN_ID, user.id.to_s)
+          Rails.logger.warn("Already sent email to #{user.id} please check Redis SET #{ProtipMailer::CAMPAIGN_ID}.")
+        else
+          Rails.logger.warn("Sending email to #{user.id}.")
+          ProtipMailer.popular_protips(user, protips, from, to).deliver
+        end
+      rescue => ex
+        Rails.logger.error("[ProtipMailer.popular_protips] Unable to send email due to '#{ex}' >>\n#{ex.backtrace.join("\n  ")}")
+        Rails.logger.ap([from, to, user, protips], :error)
+      end
     end
   end
 end