diff --git a/app/controllers/users/dossiers_controller.rb b/app/controllers/users/dossiers_controller.rb
index 88e1930a3..0b70194ef 100644
--- a/app/controllers/users/dossiers_controller.rb
+++ b/app/controllers/users/dossiers_controller.rb
@@ -314,11 +314,7 @@ module Users
 
       if @commentaire.errors.empty?
         @commentaire.dossier.update!(last_commentaire_updated_at: Time.zone.now)
-        dossier.followers_instructeurs
-          .with_instant_email_message_notifications
-          .each do |instructeur|
-          DossierMailer.notify_new_commentaire_to_instructeur(dossier, instructeur.email).deliver_later
-        end
+
         flash.notice = t('.message_send')
         redirect_to messagerie_dossier_path(dossier)
       else
diff --git a/app/mailers/avis_mailer.rb b/app/mailers/avis_mailer.rb
index 49a8b14e0..1efa8116f 100644
--- a/app/mailers/avis_mailer.rb
+++ b/app/mailers/avis_mailer.rb
@@ -20,6 +20,17 @@ class AvisMailer < ApplicationMailer
     end
   end
 
+  # i18n-tasks-use t("avis_mailer.#{action}.subject")
+  def notify_new_commentaire_to_expert(dossier, avis, expert)
+    I18n.with_locale(dossier.user_locale) do
+      @dossier = dossier
+      @avis = avis
+      @subject = default_i18n_subject(dossier_id: dossier.id, libelle_demarche: dossier.procedure.libelle)
+
+      mail(to: expert.email, subject: @subject)
+    end
+  end
+
   def self.critical_email?(action_name)
     false
   end
diff --git a/app/models/commentaire.rb b/app/models/commentaire.rb
index b461170dc..72c25e0d6 100644
--- a/app/models/commentaire.rb
+++ b/app/models/commentaire.rb
@@ -97,6 +97,8 @@ class Commentaire < ApplicationRecord
     # - Otherwise, a instructeur posted a commentaire, we need to notify the user
     if sent_by_instructeur? || sent_by_expert?
       notify_user(wait: 5.minutes)
+    elsif !sent_by_system?
+      notify_administration
     end
   end
 
@@ -108,6 +110,26 @@ class Commentaire < ApplicationRecord
     end
   end
 
+  def notify_administration
+    dossier.followers_instructeurs
+      .with_instant_email_message_notifications
+      .find_each do |instructeur|
+      DossierMailer.notify_new_commentaire_to_instructeur(dossier, instructeur.email).deliver_later
+    end
+
+    experts_contactes = Set.new
+
+    dossier.avis.includes(:expert).find_each do |avis|
+      if avis.expert.present?
+        expert_id = avis.expert.id
+        if !experts_contactes.include?(expert_id)
+          AvisMailer.notify_new_commentaire_to_expert(dossier, avis, avis.expert).deliver_later
+          experts_contactes.add(expert_id)
+        end
+      end
+    end
+  end
+
   def messagerie_available?
     return if sent_by_system?
     if dossier.present? && !dossier.messagerie_available?
diff --git a/app/views/avis_mailer/notify_new_commentaire_to_expert.html.haml b/app/views/avis_mailer/notify_new_commentaire_to_expert.html.haml
new file mode 100644
index 000000000..d3630adc7
--- /dev/null
+++ b/app/views/avis_mailer/notify_new_commentaire_to_expert.html.haml
@@ -0,0 +1,9 @@
+- content_for(:title, "#{@subject}")
+
+%p= t(:hello, scope: [:views, :shared, :greetings])
+
+%p
+  = t('.body', dossier_id: @dossier.id, libelle_demarche: @dossier.procedure.libelle)
+%p= link_to("Messagerie du dossier n°#{@dossier.id}", messagerie_expert_avis_url(procedure_id: @dossier.procedure.id, id: @avis.id))
+
+= render partial: "layouts/mailers/signature"
diff --git a/config/locales/views/avis_mailer/notify_new_commentaire_to_expert/en.yml b/config/locales/views/avis_mailer/notify_new_commentaire_to_expert/en.yml
new file mode 100644
index 000000000..ab5cdacfc
--- /dev/null
+++ b/config/locales/views/avis_mailer/notify_new_commentaire_to_expert/en.yml
@@ -0,0 +1,5 @@
+en:
+  avis_mailer:
+    notify_new_commentaire_to_expert:
+      subject: New comment posted on the file n°%{dossier_id}
+      body: A new comment has been submitted by the user on file number %{dossier_id} on the file %{libelle_demarche}
diff --git a/config/locales/views/avis_mailer/notify_new_commentaire_to_expert/fr.yml b/config/locales/views/avis_mailer/notify_new_commentaire_to_expert/fr.yml
new file mode 100644
index 000000000..83bc1105f
--- /dev/null
+++ b/config/locales/views/avis_mailer/notify_new_commentaire_to_expert/fr.yml
@@ -0,0 +1,5 @@
+fr:
+  avis_mailer:
+    notify_new_commentaire_to_expert:
+      subject: Nouveau commentaire déposé sur le dossier n°%{dossier_id}
+      body: Un nouveau commentaire a été déposé par l’usager sur le dossier n° %{dossier_id} de la démarche %{libelle_demarche}
diff --git a/spec/controllers/users/dossiers_controller_spec.rb b/spec/controllers/users/dossiers_controller_spec.rb
index 196507157..b582dbba3 100644
--- a/spec/controllers/users/dossiers_controller_spec.rb
+++ b/spec/controllers/users/dossiers_controller_spec.rb
@@ -1179,6 +1179,24 @@ describe Users::DossiersController, type: :controller do
       end
     end
 
+    context 'email notification to experts' do
+      let(:expert) { create(:expert) }
+      let(:experts_procedure) { create(:experts_procedure, expert: expert, procedure: procedure) }
+      let(:avis) { create(:avis, dossier: dossier, claimant: instructeur_with_instant_message, experts_procedure: experts_procedure) }
+      let(:avis2) { create(:avis, dossier: dossier, claimant: instructeur_with_instant_message, experts_procedure: experts_procedure) }
+
+      before do
+        allow(AvisMailer).to receive(:notify_new_commentaire_to_expert).and_return(double(deliver_later: nil))
+        avis
+        avis2
+        subject
+      end
+
+      it 'sends just one email to the expert linked to several avis on the same dossier' do
+        expect(AvisMailer).to have_received(:notify_new_commentaire_to_expert).with(dossier, avis, expert).once
+      end
+    end
+
     context 'notification' do
       before 'instructeurs have no notification before the message' do
         expect(instructeur_with_instant_message.followed_dossiers.with_notifications).to eq([])