diff --git a/app/models/mailer.rb b/app/models/mailer.rb
index ddbc7b394..148b1da16 100644
--- a/app/models/mailer.rb
+++ b/app/models/mailer.rb
@@ -670,14 +670,18 @@ class Mailer < ActionMailer::Base
           @author&.logged? ? @author.name : Setting.app_title
       end
       from = mail_from.format
-      list_id = "<#{mail_from.address.to_s.tr('@', '.')}>"
+      from_addr = mail_from.address.to_s
     rescue Mail::Field::IncompleteParseError
       # Use Setting.mail_from as it is if Mail::Address cannot parse it
       # (probably the emission address is not RFC compliant)
       from = Setting.mail_from.to_s
-      list_id = "<#{from.tr('@', '.')}>"
+      from_addr = from
     end
 
+    project_identifier =
+      Setting.include_project_in_list_id? ? self.headers['X-Redmine-Project']&.value : nil
+    list_id = "<#{[project_identifier, from_addr.tr('@', '.')].compact.join('.')}>"
+
     headers.reverse_merge! 'X-Mailer' => 'Redmine',
             'X-Redmine-Host' => Setting.host_name,
             'X-Redmine-Site' => Setting.app_title,
diff --git a/app/views/settings/_notifications.html.erb b/app/views/settings/_notifications.html.erb
index aafbe4340..342e006c3 100644
--- a/app/views/settings/_notifications.html.erb
+++ b/app/views/settings/_notifications.html.erb
@@ -7,6 +7,8 @@
 <p><%= setting_check_box :plain_text_mail %></p>
 
 <p><%= setting_check_box :show_status_changes_in_mail_subject %></p>
+
+<p><%= setting_check_box :include_project_in_list_id %></p>
 </div>
 
 <fieldset class="box" id="notified_events"><legend><%=l(:text_select_mail_notifications)%></legend>
diff --git a/config/locales/en.yml b/config/locales/en.yml
index 7d51ed1b7..6f832da31 100644
--- a/config/locales/en.yml
+++ b/config/locales/en.yml
@@ -521,6 +521,7 @@ en:
   setting_show_status_changes_in_mail_subject: Show status changes in issue mail notifications subject
   setting_project_list_defaults: Projects list defaults
   setting_twofa: Two-factor authentication
+  setting_include_project_in_list_id: Include project identifier in List-Id header
 
   permission_add_project: Create project
   permission_add_subprojects: Create subprojects
diff --git a/config/settings.yml b/config/settings.yml
index 19d3a33c7..e27add8ec 100644
--- a/config/settings.yml
+++ b/config/settings.yml
@@ -349,3 +349,5 @@ timelog_accept_future_dates:
   default: 1
 show_status_changes_in_mail_subject:
   default: 1
+include_project_in_list_id:
+  default: 1
diff --git a/test/unit/mailer_test.rb b/test/unit/mailer_test.rb
index 0506e27d2..f6108a6fc 100644
--- a/test/unit/mailer_test.rb
+++ b/test/unit/mailer_test.rb
@@ -220,7 +220,7 @@ class MailerTest < ActiveSupport::TestCase
     assert_equal 'All', mail.header['X-Auto-Response-Suppress'].to_s
     assert_equal 'auto-generated', mail.header['Auto-Submitted'].to_s
     # List-Id should not include the display name "Redmine"
-    assert_equal '<redmine.example.net>', mail.header['List-Id'].to_s
+    assert_equal '<ecookbook.redmine.example.net>', mail.header['List-Id'].to_s
     assert_equal 'Bug', mail.header['X-Redmine-Issue-Tracker'].to_s
     assert_equal 'Low', mail.header['X-Redmine-Issue-Priority'].to_s
   end