diff --git a/app/jobs/priorized_mail_delivery_job.rb b/app/jobs/priorized_mail_delivery_job.rb
new file mode 100644
index 00000000000..03ccb66ad56
--- /dev/null
+++ b/app/jobs/priorized_mail_delivery_job.rb
@@ -0,0 +1,14 @@
+class PriorizedMailDeliveryJob < ActionMailer::MailDeliveryJob
+  def queue_name
+    mailer, action_name = @arguments
+    if mailer.constantize.critical_email?(action_name)
+      super
+    else
+      custom_queue
+    end
+  end
+
+  def custom_queue
+    ENV.fetch('BULK_EMAIL_QUEUE') { Rails.application.config.action_mailer.deliver_later_queue_name }
+  end
+end
diff --git a/app/mailers/administrateur_mailer.rb b/app/mailers/administrateur_mailer.rb
index 24956ded9b3..0ed0d659867 100644
--- a/app/mailers/administrateur_mailer.rb
+++ b/app/mailers/administrateur_mailer.rb
@@ -39,9 +39,7 @@ def api_token_expiration(user, tokens)
       reply_to: CONTACT_EMAIL)
   end
 
-  private
-
-  def forced_delivery_for_action?
+  def self.critical_email?(action_name)
     action_name == "activate_before_expiration"
   end
 end
diff --git a/app/mailers/administration_mailer.rb b/app/mailers/administration_mailer.rb
index 6af3ea7c7f5..cf800c2e458 100644
--- a/app/mailers/administration_mailer.rb
+++ b/app/mailers/administration_mailer.rb
@@ -20,4 +20,8 @@ def refuse_admin(admin_email)
       subject: subject,
       reply_to: CONTACT_EMAIL)
   end
+
+  def self.critical_email?(action_name)
+    false
+  end
 end
diff --git a/app/mailers/application_mailer.rb b/app/mailers/application_mailer.rb
index adb90e82ddd..692b3f4e0aa 100644
--- a/app/mailers/application_mailer.rb
+++ b/app/mailers/application_mailer.rb
@@ -2,6 +2,7 @@ class ApplicationMailer < ActionMailer::Base
   include MailerDolistConcern
   include MailerMonitoringConcern
   include BalancedDeliveryConcern
+  include PriorityDeliveryConcern
 
   helper :application # gives access to all helpers defined within `application_helper`.
   default from: "#{APPLICATION_NAME} <#{CONTACT_EMAIL}>"
diff --git a/app/mailers/avis_mailer.rb b/app/mailers/avis_mailer.rb
index c24cd7ede7b..49a8b14e087 100644
--- a/app/mailers/avis_mailer.rb
+++ b/app/mailers/avis_mailer.rb
@@ -19,4 +19,8 @@ def avis_invitation(avis, targeted_user_link = nil) # ensure re-entrance if exis
       mail(to: email, subject: subject)
     end
   end
+
+  def self.critical_email?(action_name)
+    false
+  end
 end
diff --git a/app/mailers/concerns/balanced_delivery_concern.rb b/app/mailers/concerns/balanced_delivery_concern.rb
index f9f7bd299a2..486aadac44c 100644
--- a/app/mailers/concerns/balanced_delivery_concern.rb
+++ b/app/mailers/concerns/balanced_delivery_concern.rb
@@ -2,16 +2,16 @@ module BalancedDeliveryConcern
   extend ActiveSupport::Concern
 
   included do
-    before_action :add_delivery_method, if: :forced_delivery?
+    before_action :add_delivery_method, if: :forced_delivery_provider?
 
-    private
-
-    def forced_delivery_for_action?
-      false
+    def critical_email?
+      self.class.critical_email?(action_name)
     end
 
-    def forced_delivery?
-      SafeMailer.forced_delivery_method.present? && forced_delivery_for_action?
+    private
+
+    def forced_delivery_provider?
+      SafeMailer.forced_delivery_method.present? && critical_email?
     end
 
     def add_delivery_method
diff --git a/app/mailers/concerns/priority_delivery_concern.rb b/app/mailers/concerns/priority_delivery_concern.rb
new file mode 100644
index 00000000000..f8e68dd6f3e
--- /dev/null
+++ b/app/mailers/concerns/priority_delivery_concern.rb
@@ -0,0 +1,10 @@
+module PriorityDeliveryConcern
+  extend ActiveSupport::Concern
+  included do
+    self.delivery_job = PriorizedMailDeliveryJob
+
+    def self.critical_email?(action_name)
+      raise NotImplementedError
+    end
+  end
+end
diff --git a/app/mailers/devise_user_mailer.rb b/app/mailers/devise_user_mailer.rb
index 13f97cad412..4c910341fd1 100644
--- a/app/mailers/devise_user_mailer.rb
+++ b/app/mailers/devise_user_mailer.rb
@@ -6,6 +6,8 @@ class DeviseUserMailer < Devise::Mailer
   include MailerDolistConcern
   include MailerMonitoringConcern
   include BalancedDeliveryConcern
+  include PriorityDeliveryConcern
+
   layout 'mailers/layout'
 
   def template_paths
@@ -19,7 +21,7 @@ def confirmation_instructions(record, token, opts = {})
     super
   end
 
-  def forced_delivery_for_action?
+  def self.critical_email?(action_name)
     true
   end
 end
diff --git a/app/mailers/dossier_mailer.rb b/app/mailers/dossier_mailer.rb
index d9081708ee6..adad878a258 100644
--- a/app/mailers/dossier_mailer.rb
+++ b/app/mailers/dossier_mailer.rb
@@ -184,6 +184,10 @@ def notify_transfer(transfer)
     end
   end
 
+  def self.critical_email?(action_name)
+    false
+  end
+
   protected
 
   def prevent_perform_deliveries
diff --git a/app/mailers/expert_mailer.rb b/app/mailers/expert_mailer.rb
index e9777159edb..faa7b6054d4 100644
--- a/app/mailers/expert_mailer.rb
+++ b/app/mailers/expert_mailer.rb
@@ -22,6 +22,11 @@ def send_dossier_decision_v2(avis)
 
     mail(template_name: 'send_dossier_decision', to: email, subject: subject)
   end
+
+  def self.critical_email?(action_name)
+    false
+  end
+
 end
 
 def decision_dossier(dossier)
diff --git a/app/mailers/groupe_gestionnaire_mailer.rb b/app/mailers/groupe_gestionnaire_mailer.rb
index b5c4debac6f..cecde91afe8 100644
--- a/app/mailers/groupe_gestionnaire_mailer.rb
+++ b/app/mailers/groupe_gestionnaire_mailer.rb
@@ -18,4 +18,8 @@ def notify_added_gestionnaires(groupe_gestionnaire, added_gestionnaires, current
 
     mail(bcc: added_gestionnaire_emails, subject: subject)
   end
+
+  def self.critical_email?(action_name)
+    false
+  end
 end
diff --git a/app/mailers/groupe_instructeur_mailer.rb b/app/mailers/groupe_instructeur_mailer.rb
index eb0c6ceb816..76f0e917c59 100644
--- a/app/mailers/groupe_instructeur_mailer.rb
+++ b/app/mailers/groupe_instructeur_mailer.rb
@@ -27,4 +27,8 @@ def notify_added_instructeurs(group, added_instructeurs, current_instructeur_ema
 
     mail(bcc: added_instructeur_emails, subject: subject)
   end
+
+  def self.critical_email?(action_name)
+    false
+  end
 end
diff --git a/app/mailers/instructeur_mailer.rb b/app/mailers/instructeur_mailer.rb
index af175ff8627..0a258485027 100644
--- a/app/mailers/instructeur_mailer.rb
+++ b/app/mailers/instructeur_mailer.rb
@@ -45,9 +45,7 @@ def send_notifications(instructeur, data)
     mail(to: instructeur.email, subject: subject)
   end
 
-  private
-
-  def forced_delivery_for_action?
+  def self.critical_email?(action_name)
     action_name == "send_login_token"
   end
 end
diff --git a/app/mailers/invite_mailer.rb b/app/mailers/invite_mailer.rb
index a9d0b38b3c7..d9c892b91e3 100644
--- a/app/mailers/invite_mailer.rb
+++ b/app/mailers/invite_mailer.rb
@@ -33,7 +33,7 @@ def send_mail(invite, subject, reply_to)
       reply_to: reply_to)
   end
 
-  def forced_delivery_for_action?
+  def self.critical_email?(action_name)
     true
   end
 end
diff --git a/app/mailers/notification_mailer.rb b/app/mailers/notification_mailer.rb
index 23b9a605711..3b9e5a80fd2 100644
--- a/app/mailers/notification_mailer.rb
+++ b/app/mailers/notification_mailer.rb
@@ -48,6 +48,10 @@ def self.send_pending_correction(dossier)
     with(dossier: dossier).send_notification
   end
 
+  def self.critical_email?(action_name)
+    false
+  end
+
   private
 
   def set_services_publics_plus
diff --git a/app/mailers/preactivate_users_mailer.rb b/app/mailers/preactivate_users_mailer.rb
index c3c9eb25f70..1c24a91abe7 100644
--- a/app/mailers/preactivate_users_mailer.rb
+++ b/app/mailers/preactivate_users_mailer.rb
@@ -30,4 +30,9 @@ def reinvite(model, model_name)
       reply_to: CONTACT_EMAIL,
       body: body)
   end
+
+  def self.critical_email?(action_name)
+    false
+  end
+
 end
diff --git a/app/mailers/resend_attestation_mailer.rb b/app/mailers/resend_attestation_mailer.rb
index df3f627bf89..f55451afb00 100644
--- a/app/mailers/resend_attestation_mailer.rb
+++ b/app/mailers/resend_attestation_mailer.rb
@@ -8,6 +8,11 @@ def resend_attestation(dossier)
     mail(to: to, subject: subject, body: body(dossier))
   end
 
+  def self.critical_email?(action_name)
+    false
+  end
+
+
   private
 
   def body(dossier)
diff --git a/app/mailers/super_admin_mailer.rb b/app/mailers/super_admin_mailer.rb
index 75c838652c7..edbb050b604 100644
--- a/app/mailers/super_admin_mailer.rb
+++ b/app/mailers/super_admin_mailer.rb
@@ -4,4 +4,8 @@ def dolist_report(to, csv_path)
 
     mail(to: to, subject: "Dolist report", body: "Ci-joint le rapport d'emails récents envoyés via Dolist.")
   end
+
+  def self.critical_email?(action_name)
+    false
+  end
 end
diff --git a/app/mailers/user_mailer.rb b/app/mailers/user_mailer.rb
index 4e8f97db9d6..85b1f3ca609 100644
--- a/app/mailers/user_mailer.rb
+++ b/app/mailers/user_mailer.rb
@@ -67,7 +67,7 @@ def send_archive(administrateur_or_instructeur, procedure, archive)
     mail(to: administrateur_or_instructeur.email, subject: subject)
   end
 
-  def forced_delivery_for_action?
+  def self.critical_email?(action_name)
     ['france_connect_merge_confirmation', "new_account_warning", "ask_for_merge", "invite_instructeur"].include?(action_name)
   end
 end
diff --git a/config/env.example.optional b/config/env.example.optional
index e177bf40dc2..d2448480948 100644
--- a/config/env.example.optional
+++ b/config/env.example.optional
@@ -236,3 +236,4 @@ DS_LOG_LEVEL='info'
 # Admins group usage (gestionnaire de groupes d'administrateurs)
 # can be removed if needed when EVERY PARTS of the feature will be merged / only used in routes.rb
 ADMINS_GROUP_ENABLED="disabled"
+BULK_EMAIL_QUEUE="low_priority"
diff --git a/config/environments/development.rb b/config/environments/development.rb
index 485fbc0c5b5..0749590943b 100644
--- a/config/environments/development.rb
+++ b/config/environments/development.rb
@@ -86,7 +86,7 @@
     helo: ENV['HELO_ENABLED'] == 'enabled' ? 100 : 0,
     letter_opener: ENV['HELO_ENABLED'] == 'enabled' ? 0 : 100
   }
-  config.action_mailer.delivery_method = :balancer
+  config.action_mailer.delivery_method = :letter_opener_web
 
   config.action_mailer.default_url_options = { host: ENV.fetch("APP_HOST") }
   config.action_mailer.asset_host = "http://" + ENV.fetch("APP_HOST")
diff --git a/spec/mailers/administrateur_mailer_spec.rb b/spec/mailers/administrateur_mailer_spec.rb
index 64b7fffb7b7..a42edb2b3b0 100644
--- a/spec/mailers/administrateur_mailer_spec.rb
+++ b/spec/mailers/administrateur_mailer_spec.rb
@@ -1,32 +1,57 @@
 RSpec.describe AdministrateurMailer, type: :mailer do
   let(:procedure) { create(:procedure) }
   let(:admin_email) { 'administrateur@email.fr' }
+
   describe '.notify_procedure_expires_when_termine_forced' do
     subject { described_class.notify_procedure_expires_when_termine_forced(admin_email, procedure) }
+
     it { expect(subject.to).to eq([admin_email]) }
     it { expect(subject.subject).to include("La suppression automatique des dossiers a été activée sur la démarche") }
+
+    context 'when perform_later is called' do
+      let(:custom_queue) { 'low_priority' }
+      before { ENV['BULK_EMAIL_QUEUE'] = custom_queue }
+      it 'enqueues email is custom queue for low priority delivery' do
+        expect { subject.deliver_later }.to have_enqueued_job.on_queue(custom_queue)
+      end
+    end
   end
+
   describe '.activate_before_expiration' do
     let(:user) { create(:user, reset_password_sent_at: 2.days.ago) }
     let(:token) { SecureRandom.hex }
+    subject { described_class.activate_before_expiration(user, token) }
 
     context 'without SafeMailer configured' do
-      subject { described_class.activate_before_expiration(user, token) }
       it { expect(subject[BalancerDeliveryMethod::FORCE_DELIVERY_METHOD_HEADER]&.value).to eq(nil) }
     end
 
     context 'with SafeMailer configured' do
       let(:forced_delivery_method) { :kikoo }
       before { allow(SafeMailer).to receive(:forced_delivery_method).and_return(forced_delivery_method) }
-      subject { described_class.activate_before_expiration(user, token) }
       it { expect(subject[BalancerDeliveryMethod::FORCE_DELIVERY_METHOD_HEADER]&.value).to eq(forced_delivery_method.to_s) }
     end
+
+    context 'when perform_later is called' do
+      it 'enqueues email in default queue for high priority delivery' do
+  expect { subject.deliver_later }.to have_enqueued_job.on_queue(Rails.application.config.action_mailer.deliver_later_queue_name)
+end
+    end
   end
 
   describe '.notify_service_without_siret' do
     subject { described_class.notify_service_without_siret(admin_email) }
+
     it { expect(subject.to).to eq([admin_email]) }
     it { expect(subject.subject).to eq("Siret manquant sur un de vos services") }
     it { expect(subject.body).to include("un de vos services n'a pas son siret renseigné") }
+
+    context 'when perform_later is called' do
+      let(:custom_queue) { 'low_priority' }
+      before { ENV['BULK_EMAIL_QUEUE'] = custom_queue }
+      it 'enqueues email is custom queue for low priority delivery' do
+        expect { subject.deliver_later }.to have_enqueued_job.on_queue(custom_queue)
+      end
+    end
   end
 end
diff --git a/spec/mailers/devise_user_mailer_spec.rb b/spec/mailers/devise_user_mailer_spec.rb
index f3c82701f98..e0093028c1a 100644
--- a/spec/mailers/devise_user_mailer_spec.rb
+++ b/spec/mailers/devise_user_mailer_spec.rb
@@ -2,15 +2,22 @@
   let(:user) { create(:user) }
   let(:token) { SecureRandom.hex }
   describe '.confirmation_instructions' do
+    subject { described_class.confirmation_instructions(user, token, opts = {}) }
+
     context 'without SafeMailer configured' do
-      subject { described_class.confirmation_instructions(user, token, opts = {}) }
       it { expect(subject[BalancerDeliveryMethod::FORCE_DELIVERY_METHOD_HEADER]&.value).to eq(nil) }
     end
+
     context 'with SafeMailer configured' do
       let(:forced_delivery_method) { :kikoo }
       before { allow(SafeMailer).to receive(:forced_delivery_method).and_return(forced_delivery_method) }
-      subject { described_class.confirmation_instructions(user, token, opts = {}) }
       it { expect(subject[BalancerDeliveryMethod::FORCE_DELIVERY_METHOD_HEADER]&.value).to eq(forced_delivery_method.to_s) }
     end
+
+    context 'when perform_later is called' do
+      it 'enqueues email in default queue for high priority delivery' do
+  expect { subject.deliver_later }.to have_enqueued_job.on_queue(Rails.application.config.action_mailer.deliver_later_queue_name)
+end
+    end
   end
 end
diff --git a/spec/mailers/instructeur_mailer_spec.rb b/spec/mailers/instructeur_mailer_spec.rb
index ce390bb64bc..e84dfde82cb 100644
--- a/spec/mailers/instructeur_mailer_spec.rb
+++ b/spec/mailers/instructeur_mailer_spec.rb
@@ -3,27 +3,40 @@
     let(:sender) { create(:instructeur) }
     let(:recipient) { create(:instructeur) }
     let(:dossier) { create(:dossier) }
-
     subject { described_class.send_dossier(sender, dossier, recipient) }
 
     it { expect(subject.body).to include('Bonjour') }
+
+    context 'when perform_later is called' do
+      let(:custom_queue) { 'low_priority' }
+      before { ENV['BULK_EMAIL_QUEUE'] = custom_queue }
+
+      it 'enqueues email is custom queue for low priority delivery' do
+        expect { subject.deliver_later }.to have_enqueued_job.on_queue(custom_queue)
+      end
+    end
   end
 
   describe '#send_login_token' do
     let(:user) { create(:instructeur) }
     let(:token) { SecureRandom.hex }
+    subject { described_class.send_login_token(user, token) }
 
     context 'without SafeMailer configured' do
-      subject { described_class.send_login_token(user, token) }
       it { expect(subject[BalancerDeliveryMethod::FORCE_DELIVERY_METHOD_HEADER]&.value).to eq(nil) }
     end
 
     context 'with SafeMailer configured' do
       let(:forced_delivery_method) { :kikoo }
       before { allow(SafeMailer).to receive(:forced_delivery_method).and_return(forced_delivery_method) }
-      subject { described_class.send_login_token(user, token) }
       it { expect(subject[BalancerDeliveryMethod::FORCE_DELIVERY_METHOD_HEADER]&.value).to eq(forced_delivery_method.to_s) }
     end
+
+    context 'when perform_later is called' do
+      it 'enqueues email in default queue for high priority delivery' do
+        expect { subject.deliver_later }.to have_enqueued_job.on_queue(Rails.application.config.action_mailer.deliver_later_queue_name)
+      end
+    end
   end
 
   describe '#last_week_overview' do
@@ -62,5 +75,14 @@
         expect(subject.body).to be_blank
       end
     end
+
+    context 'when perform_later is called' do
+      let(:custom_queue) { 'low_priority' }
+      before { ENV['BULK_EMAIL_QUEUE'] = custom_queue }
+
+      it 'enqueues email is custom queue for low priority delivery' do
+        expect { subject.deliver_later }.to have_enqueued_job.on_queue(custom_queue)
+      end
+    end
   end
 end
diff --git a/spec/mailers/invite_mailer_spec.rb b/spec/mailers/invite_mailer_spec.rb
index 0e5102dc9f0..9500e5136c7 100644
--- a/spec/mailers/invite_mailer_spec.rb
+++ b/spec/mailers/invite_mailer_spec.rb
@@ -1,9 +1,8 @@
 RSpec.describe InviteMailer, type: :mailer do
-  let(:deliver) { mailer.deliver_now }
+  let(:deliver) { subject.deliver_now }
+  subject { InviteMailer.invite_user(invite) }
 
   describe '.invite_user' do
-    let(:mailer) { InviteMailer.invite_user(invite) }
-
     let(:invite) { create(:invite, user: create(:user)) }
     it 'creates a target_user_link' do
       expect { deliver }
@@ -20,29 +19,34 @@
          end
 
          begin
-           mailer.body
+           subject.body
          rescue => e
            nil
          end
 
-         mailer.body
+         subject.body
          expect(TargetedUserLink.where(target_model: invite, user: invite.user).count).to eq(1)
        end
     end
 
     context 'without SafeMailer configured' do
-      it { expect(mailer[BalancerDeliveryMethod::FORCE_DELIVERY_METHOD_HEADER]&.value).to eq(nil) }
+      it { expect(subject[BalancerDeliveryMethod::FORCE_DELIVERY_METHOD_HEADER]&.value).to eq(nil) }
     end
 
     context 'with SafeMailer configured' do
       let(:forced_delivery_method) { :kikoo }
       before { allow(SafeMailer).to receive(:forced_delivery_method).and_return(forced_delivery_method) }
-      it { expect(mailer[BalancerDeliveryMethod::FORCE_DELIVERY_METHOD_HEADER]&.value).to eq(forced_delivery_method.to_s) }
+      it { expect(subject[BalancerDeliveryMethod::FORCE_DELIVERY_METHOD_HEADER]&.value).to eq(forced_delivery_method.to_s) }
+    end
+
+    context 'when perform_later is called' do
+      it 'enqueues email in default queue for high priority delivery' do
+        expect { invite }.to have_enqueued_job.on_queue(Rails.application.config.action_mailer.deliver_later_queue_name)
+      end
     end
   end
 
   describe '.invite_guest' do
-    let(:mailer) { InviteMailer.invite_guest(invite) }
     let(:invite) { create(:invite, user: nil, email: 'kikoo@lol.fr') }
 
     it 'creates a target_user_link' do
@@ -69,14 +73,20 @@
          end
 
          begin
-           mailer.body
+           subject.body
          rescue => e
            nil
          end
 
-         mailer.body
+         subject.body
          expect(TargetedUserLink.where(target_model: invite, user: invite.user).count).to eq(1)
        end
     end
+
+    context 'when perform_later is called' do
+      it 'enqueues email in default queue for high priority delivery' do
+        expect { invite }.to have_enqueued_job.on_queue(Rails.application.config.action_mailer.deliver_later_queue_name)
+      end
+    end
   end
 end
diff --git a/spec/mailers/user_mailer_spec.rb b/spec/mailers/user_mailer_spec.rb
index b741baf2ead..507b9d8b09a 100644
--- a/spec/mailers/user_mailer_spec.rb
+++ b/spec/mailers/user_mailer_spec.rb
@@ -1,5 +1,5 @@
 RSpec.describe UserMailer, type: :mailer do
-  let(:user) { build(:user) }
+  let(:user) { create(:user) }
 
   describe '.new_account_warning' do
     subject { described_class.new_account_warning(user) }
@@ -25,6 +25,12 @@
       before { allow(SafeMailer).to receive(:forced_delivery_method).and_return(forced_delivery_method) }
       it { expect(subject[BalancerDeliveryMethod::FORCE_DELIVERY_METHOD_HEADER]&.value).to eq(forced_delivery_method.to_s) }
     end
+
+    context 'when perform_later is called' do
+      it 'enqueues email in default queue for high priority delivery' do
+        expect { subject.deliver_later }.to have_enqueued_job.on_queue(Rails.application.config.action_mailer.deliver_later_queue_name)
+      end
+    end
   end
 
   describe '.ask_for_merge' do
@@ -44,6 +50,12 @@
       before { allow(SafeMailer).to receive(:forced_delivery_method).and_return(forced_delivery_method) }
       it { expect(subject[BalancerDeliveryMethod::FORCE_DELIVERY_METHOD_HEADER]&.value).to eq(forced_delivery_method.to_s) }
     end
+
+    context 'when perform_later is called' do
+      it 'enqueues email in default queue for high priority delivery' do
+        expect { subject.deliver_later }.to have_enqueued_job.on_queue(Rails.application.config.action_mailer.deliver_later_queue_name)
+      end
+    end
   end
 
   describe '.france_connect_merge_confirmation' do
@@ -64,6 +76,12 @@
       before { allow(SafeMailer).to receive(:forced_delivery_method).and_return(forced_delivery_method) }
       it { expect(subject[BalancerDeliveryMethod::FORCE_DELIVERY_METHOD_HEADER]&.value).to eq(forced_delivery_method.to_s) }
     end
+
+    context 'when perform_later is called' do
+      it 'enqueues email in default queue for high priority delivery' do
+        expect { subject.deliver_later }.to have_enqueued_job.on_queue(Rails.application.config.action_mailer.deliver_later_queue_name)
+      end
+    end
   end
 
   describe '.send_archive' do
@@ -84,5 +102,14 @@
       it { expect(subject.body).to have_link('Consulter mes archives', href: admin_procedure_archives_url(procedure)) }
       it { expect(subject.body).to have_link("#{procedure.id} − #{procedure.libelle}", href: admin_procedure_url(procedure)) }
     end
+
+    context 'when perform_later is called' do
+      let(:role) { create(:administrateur) }
+      let(:custom_queue) { 'low_priority' }
+      before { ENV['BULK_EMAIL_QUEUE'] = custom_queue }
+      it 'enqueues email is custom queue for low priority delivery' do
+        expect { subject.deliver_later }.to have_enqueued_job.on_queue(custom_queue)
+      end
+    end
   end
 end