diff --git a/app/controllers/users/registrations_controller.rb b/app/controllers/users/registrations_controller.rb
index b1787becf..95be35e5b 100644
--- a/app/controllers/users/registrations_controller.rb
+++ b/app/controllers/users/registrations_controller.rb
@@ -17,7 +17,7 @@ class Users::RegistrationsController < Devise::RegistrationsController
   def create
     user = User.find_by(email: params[:user][:email])
     if user.present?
-      UserMailer.new_account_warning(user).deliver
+      UserMailer.new_account_warning(user).deliver_later
       flash.notice = t('devise.registrations.signed_up_but_unconfirmed')
       redirect_to root_path
     else
diff --git a/app/mailers/user_mailer.rb b/app/mailers/user_mailer.rb
index c0b8a7547..f4cdab83d 100644
--- a/app/mailers/user_mailer.rb
+++ b/app/mailers/user_mailer.rb
@@ -5,6 +5,6 @@ class UserMailer < ApplicationMailer
     @user = user
     @subject = "Demande de création de compte"
 
-    mail(to: user.email, subject: subject)
+    mail(to: user.email, subject: @subject)
   end
 end
diff --git a/spec/controllers/users/registrations_controller_spec.rb b/spec/controllers/users/registrations_controller_spec.rb
index 8fe725f9f..baebdd389 100644
--- a/spec/controllers/users/registrations_controller_spec.rb
+++ b/spec/controllers/users/registrations_controller_spec.rb
@@ -37,7 +37,7 @@ describe Users::RegistrationsController, type: :controller do
       let!(:existing_user) { create(:user, email: email, password: password) }
 
       before do
-        allow(UserMailer).to receive(:new_account_warning).and_return(double(deliver: 'deliver'))
+        allow(UserMailer).to receive(:new_account_warning).and_return(double(deliver_later: 'deliver'))
         subject
       end