diff --git a/app/listeners/notification_listener.rb b/app/listeners/notification_listener.rb
index 7f712e896..4192ed250 100644
--- a/app/listeners/notification_listener.rb
+++ b/app/listeners/notification_listener.rb
@@ -31,7 +31,8 @@ class NotificationListener < BaseListener
     message, account = extract_message_and_account(event)
     conversation = message.conversation
 
-    generate_notifications_for_mentions(message, account)
+    # Check if the message contains any mentions
+    Messages::MentionService.new(message: message).perform
 
     # only want to notify agents about customer messages
     return unless message.incoming?
@@ -44,34 +45,4 @@ class NotificationListener < BaseListener
       primary_actor: message
     ).perform
   end
-
-  private
-
-  def get_valid_mentioned_ids(mentioned_ids, inbox)
-    valid_mentionable_ids = inbox.account.administrators.map(&:id) + inbox.members.map(&:id)
-    # Intersection of ids
-    mentioned_ids & valid_mentionable_ids.uniq.map(&:to_s)
-  end
-
-  def generate_notifications_for_mentions(message, account)
-    return unless message.private?
-
-    return if message.content.blank?
-
-    mentioned_ids = message.content.scan(%r{\(mention://(user|team)/(\d+)/(.+?)\)}).map(&:second).uniq
-
-    return if mentioned_ids.blank?
-
-    valid_mentioned_ids = get_valid_mentioned_ids(mentioned_ids, message.inbox)
-    Conversations::UserMentionJob.perform_later(valid_mentioned_ids, message.conversation.id, account.id)
-
-    valid_mentioned_ids.each do |user_id|
-      NotificationBuilder.new(
-        notification_type: 'conversation_mention',
-        user: User.find(user_id),
-        account: account,
-        primary_actor: message
-      ).perform
-    end
-  end
 end
diff --git a/app/services/messages/mention_service.rb b/app/services/messages/mention_service.rb
new file mode 100644
index 000000000..aa8cbfce2
--- /dev/null
+++ b/app/services/messages/mention_service.rb
@@ -0,0 +1,48 @@
+class Messages::MentionService
+  pattr_initialize [:message!]
+
+  def perform
+    return unless valid_mention_message?(message)
+
+    validated_mentioned_ids = filter_mentioned_ids_by_inbox
+    return if validated_mentioned_ids.blank?
+
+    Conversations::UserMentionJob.perform_later(validated_mentioned_ids, message.conversation.id, message.account.id)
+    generate_notifications_for_mentions(validated_mentioned_ids)
+    add_mentioned_users_as_participants(validated_mentioned_ids)
+  end
+
+  private
+
+  def valid_mention_message?(message)
+    message.private? && message.content.present? && mentioned_ids.present?
+  end
+
+  def mentioned_ids
+    @mentioned_ids ||= message.content.scan(%r{\(mention://(user|team)/(\d+)/(.+?)\)}).map(&:second).uniq
+  end
+
+  def filter_mentioned_ids_by_inbox
+    inbox = message.inbox
+    valid_mentionable_ids = inbox.account.administrators.map(&:id) + inbox.members.map(&:id)
+    # Intersection of ids
+    mentioned_ids & valid_mentionable_ids.uniq.map(&:to_s)
+  end
+
+  def generate_notifications_for_mentions(validated_mentioned_ids)
+    validated_mentioned_ids.each do |user_id|
+      NotificationBuilder.new(
+        notification_type: 'conversation_mention',
+        user: User.find(user_id),
+        account: message.account,
+        primary_actor: message
+      ).perform
+    end
+  end
+
+  def add_mentioned_users_as_participants(validated_mentioned_ids)
+    validated_mentioned_ids.each do |user_id|
+      message.conversation.conversation_participants.find_or_create_by!(user_id: user_id)
+    end
+  end
+end
diff --git a/spec/listeners/notification_listener_spec.rb b/spec/listeners/notification_listener_spec.rb
index e581e9ac6..f30ec6391 100644
--- a/spec/listeners/notification_listener_spec.rb
+++ b/spec/listeners/notification_listener_spec.rb
@@ -4,7 +4,6 @@ describe NotificationListener do
   let!(:account) { create(:account) }
   let!(:user) { create(:user, account: account) }
   let!(:first_agent) { create(:user, account: account) }
-  let!(:second_agent) { create(:user, account: account) }
   let!(:agent_with_out_notification) { create(:user, account: account) }
   let!(:inbox) { create(:inbox, account: account) }
   let!(:conversation) { create(:conversation, account: account, inbox: inbox, assignee: user) }
@@ -55,68 +54,29 @@ describe NotificationListener do
       notification_setting.save!
     end
 
-    context 'when message contains mention' do
-      it 'creates notifications for inbox member who was mentioned' do
-        builder = double
-        allow(NotificationBuilder).to receive(:new).and_return(builder)
-        allow(builder).to receive(:perform)
+    it 'will call mention service' do
+      mention_service = instance_double(Messages::MentionService)
+      allow(Messages::MentionService).to receive(:new).and_return(mention_service)
+      allow(mention_service).to receive(:perform)
 
-        create(:inbox_member, user: first_agent, inbox: inbox)
-        conversation.reload
+      create(:inbox_member, user: first_agent, inbox: inbox)
+      conversation.reload
 
-        message = build(
-          :message,
-          conversation: conversation,
-          account: account,
-          content: "hi [#{first_agent.name}](mention://user/#{first_agent.id}/#{first_agent.name})",
-          private: true
-        )
+      message = build(
+        :message,
+        conversation: conversation,
+        account: account,
+        content: "hi [#{first_agent.name}](mention://user/#{first_agent.id}/#{first_agent.name})",
+        private: true
+      )
 
-        event = Events::Base.new(event_name, Time.zone.now, message: message)
-        listener.message_created(event)
-
-        expect(NotificationBuilder).to have_received(:new).with(notification_type: 'conversation_mention',
-                                                                user: first_agent,
-                                                                account: account,
-                                                                primary_actor: message)
-      end
-    end
-
-    context 'when message contains multiple mentions' do
-      it 'creates notifications for inbox member who was mentioned' do
-        builder = double
-        allow(NotificationBuilder).to receive(:new).and_return(builder)
-        allow(builder).to receive(:perform)
-        create(:inbox_member, user: first_agent, inbox: inbox)
-        create(:inbox_member, user: second_agent, inbox: inbox)
-        conversation.reload
-
-        message = build(
-          :message,
-          conversation: conversation,
-          account: account,
-          content: "hey [#{second_agent.name}](mention://user/#{second_agent.id}/#{second_agent.name})/
-                    [#{first_agent.name}](mention://user/#{first_agent.id}/#{first_agent.name}),
-                     please look in to this?",
-          private: true
-        )
-
-        event = Events::Base.new(event_name, Time.zone.now, message: message)
-        listener.message_created(event)
-
-        expect(NotificationBuilder).to have_received(:new).with(notification_type: 'conversation_mention',
-                                                                user: second_agent,
-                                                                account: account,
-                                                                primary_actor: message)
-        expect(NotificationBuilder).to have_received(:new).with(notification_type: 'conversation_mention',
-                                                                user: first_agent,
-                                                                account: account,
-                                                                primary_actor: message)
-      end
+      expect(mention_service).to receive(:perform)
+      event = Events::Base.new(event_name, Time.zone.now, message: message)
+      listener.message_created(event)
     end
 
     context 'when message content is empty' do
-      it 'creates notifications' do
+      it 'will be processed correctly' do
         builder = double
         allow(NotificationBuilder).to receive(:new).and_return(builder)
         allow(builder).to receive(:perform)
diff --git a/spec/services/messages/mention_service_spec.rb b/spec/services/messages/mention_service_spec.rb
new file mode 100644
index 000000000..21484ab13
--- /dev/null
+++ b/spec/services/messages/mention_service_spec.rb
@@ -0,0 +1,70 @@
+require 'rails_helper'
+
+describe Messages::MentionService do
+  let!(:account) { create(:account) }
+  let!(:user) { create(:user, account: account) }
+  let!(:first_agent) { create(:user, account: account) }
+  let!(:second_agent) { create(:user, account: account) }
+  let!(:inbox) { create(:inbox, account: account) }
+  let!(:conversation) { create(:conversation, account: account, inbox: inbox, assignee: user) }
+  let(:builder) { double }
+
+  before do
+    create(:inbox_member, user: first_agent, inbox: inbox)
+    create(:inbox_member, user: second_agent, inbox: inbox)
+    conversation.reload
+    allow(NotificationBuilder).to receive(:new).and_return(builder)
+    allow(builder).to receive(:perform)
+  end
+
+  context 'when message contains mention' do
+    it 'creates notifications for inbox member who was mentioned' do
+      message = build(
+        :message,
+        conversation: conversation,
+        account: account,
+        content: "hi [#{first_agent.name}](mention://user/#{first_agent.id}/#{first_agent.name})",
+        private: true
+      )
+
+      described_class.new(message: message).perform
+
+      expect(NotificationBuilder).to have_received(:new).with(notification_type: 'conversation_mention',
+                                                              user: first_agent,
+                                                              account: account,
+                                                              primary_actor: message)
+    end
+  end
+
+  context 'when message contains multiple mentions' do
+    let(:message) do
+      build(
+        :message,
+        conversation: conversation,
+        account: account,
+        content: "hey [#{second_agent.name}](mention://user/#{second_agent.id}/#{second_agent.name})/
+                  [#{first_agent.name}](mention://user/#{first_agent.id}/#{first_agent.name}),
+                   please look in to this?",
+        private: true
+      )
+    end
+
+    it 'creates notifications for inbox member who was mentioned' do
+      described_class.new(message: message).perform
+
+      expect(NotificationBuilder).to have_received(:new).with(notification_type: 'conversation_mention',
+                                                              user: second_agent,
+                                                              account: account,
+                                                              primary_actor: message)
+      expect(NotificationBuilder).to have_received(:new).with(notification_type: 'conversation_mention',
+                                                              user: first_agent,
+                                                              account: account,
+                                                              primary_actor: message)
+    end
+
+    it 'add the users to the participants list' do
+      described_class.new(message: message).perform
+      expect(conversation.conversation_participants.map(&:user_id)).to match_array([first_agent.id, second_agent.id])
+    end
+  end
+end