diff --git a/CHANGELOG b/CHANGELOG
index a52ac53bae772d6c642c4ff71e04f2953cd14da3..9c84ef90d715aff9d262f960b76ef2e277b3c009 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -271,6 +271,10 @@ v 8.11.6
 v 8.11.5
   - Optimize branch lookups and force a repository reload for Repository#find_branch. !6087
   - Fix member expiration date picker after update. !6184
+  - Add configurable email subject suffix
+
+v 8.11.5 (unreleased)
+  - Optimize branch lookups and force a repository reload for Repository#find_branch
   - Fix suggested colors options for new labels in the admin area. !6138
   - Optimize discussion notes resolving and unresolving
   - Fix GitLab import button
diff --git a/app/mailers/notify.rb b/app/mailers/notify.rb
index 29f1c52777644371cf0ab8338c0a56b57be44d67..1321b42ddf43f4bc4e5e81e9814d9b8a00fdb13f 100644
--- a/app/mailers/notify.rb
+++ b/app/mailers/notify.rb
@@ -92,6 +92,7 @@ def subject(*extra)
     subject = ""
     subject << "#{@project.name} | " if @project
     subject << extra.join(' | ') if extra.present?
+    subject << " | #{Gitlab.config.gitlab.email_subject_suffix}" if Gitlab.config.gitlab.email_subject_suffix.length > 0
     subject
   end
 
diff --git a/config/gitlab.yml.example b/config/gitlab.yml.example
index 1470a6e2550baf123c40c5765fb6dad942c08169..a79356923b2bfbe8c835a86c739ee20a5d815772 100644
--- a/config/gitlab.yml.example
+++ b/config/gitlab.yml.example
@@ -70,6 +70,7 @@ production: &base
     email_from: example@example.com
     email_display_name: GitLab
     email_reply_to: noreply@example.com
+    email_subject_suffix: ''
 
     # Email server smtp settings are in config/initializers/smtp_settings.rb.sample
 
diff --git a/config/initializers/1_settings.rb b/config/initializers/1_settings.rb
index 195108b921b749f8a85bc733450f0992153ce0b6..c5ed2162c9248de87ebeb962b3a8bd697e682a1f 100644
--- a/config/initializers/1_settings.rb
+++ b/config/initializers/1_settings.rb
@@ -186,6 +186,7 @@ def host(url)
 Settings.gitlab['email_from'] ||= ENV['GITLAB_EMAIL_FROM'] || "gitlab@#{Settings.gitlab.host}"
 Settings.gitlab['email_display_name'] ||= ENV['GITLAB_EMAIL_DISPLAY_NAME'] || 'GitLab'
 Settings.gitlab['email_reply_to'] ||= ENV['GITLAB_EMAIL_REPLY_TO'] || "noreply@#{Settings.gitlab.host}"
+Settings.gitlab['email_subject_suffix'] ||= ENV['GITLAB_EMAIL_SUBJECT_SUFFIX'] || ""
 Settings.gitlab['base_url']   ||= Settings.send(:build_base_gitlab_url)
 Settings.gitlab['url']        ||= Settings.send(:build_gitlab_url)
 Settings.gitlab['user']       ||= 'git'
diff --git a/doc/administration/environment_variables.md b/doc/administration/environment_variables.md
index 7f53915a4d7c861b023bdf7410483172ee387467..b4a953d1ccc0a0aea42cf07335b463f9b4f6c1d3 100644
--- a/doc/administration/environment_variables.md
+++ b/doc/administration/environment_variables.md
@@ -13,15 +13,17 @@ override certain values.
 
 Variable | Type | Description
 -------- | ---- | -----------
-`GITLAB_ROOT_PASSWORD`      | string | Sets the password for the `root` user on installation
-`GITLAB_HOST`               | string | The full URL of the GitLab server (including `http://` or `https://`)
-`RAILS_ENV`                 | string | The Rails environment; can be one of `production`, `development`, `staging` or `test`
-`DATABASE_URL`              | string | The database URL; is of the form: `postgresql://localhost/blog_development`
-`GITLAB_EMAIL_FROM`         | string | The e-mail address used in the "From" field in e-mails sent by GitLab
-`GITLAB_EMAIL_DISPLAY_NAME` | string | The name used in the "From" field in e-mails sent by GitLab
-`GITLAB_EMAIL_REPLY_TO`     | string | The e-mail address used in the "Reply-To" field in e-mails sent by GitLab
-`GITLAB_UNICORN_MEMORY_MIN` | integer | The minimum memory threshold (in bytes) for the Unicorn worker killer
-`GITLAB_UNICORN_MEMORY_MAX` | integer | The maximum memory threshold (in bytes) for the Unicorn worker killer
+`GITLAB_ROOT_PASSWORD`        | string  | Sets the password for the `root` user on installation
+`GITLAB_HOST`                 | string  | The full URL of the GitLab server (including `http://` or `https://`)
+`RAILS_ENV`                   | string  | The Rails environment; can be one of `production`, `development`, `staging` or `test`
+`DATABASE_URL`                | string  | The database URL; is of the form: `postgresql://localhost/blog_development`
+`GITLAB_EMAIL_FROM`           | string  | The e-mail address used in the "From" field in e-mails sent by GitLab
+`GITLAB_EMAIL_DISPLAY_NAME`   | string  | The name used in the "From" field in e-mails sent by GitLab
+`GITLAB_EMAIL_REPLY_TO`       | string  | The e-mail address used in the "Reply-To" field in e-mails sent by GitLab
+`GITLAB_EMAIL_REPLY_TO`       | string  | The e-mail address used in the "Reply-To" field in e-mails sent by GitLab
+`GITLAB_EMAIL_SUBJECT_SUFFIX` | string  | The e-mail subject suffix used in e-mails sent by GitLab
+`GITLAB_UNICORN_MEMORY_MIN`   | integer | The minimum memory threshold (in bytes) for the Unicorn worker killer
+`GITLAB_UNICORN_MEMORY_MAX`   | integer | The maximum memory threshold (in bytes) for the Unicorn worker killer
 
 ## Complete database variables
 
diff --git a/spec/mailers/shared/notify.rb b/spec/mailers/shared/notify.rb
index 5c9851f14c79cb1e716070907ec4e7a77ff5ba11..de1d89955349fecd0166f6f6c97202a66819faa8 100644
--- a/spec/mailers/shared/notify.rb
+++ b/spec/mailers/shared/notify.rb
@@ -2,6 +2,7 @@
   let(:gitlab_sender_display_name) { Gitlab.config.gitlab.email_display_name }
   let(:gitlab_sender) { Gitlab.config.gitlab.email_from }
   let(:gitlab_sender_reply_to) { Gitlab.config.gitlab.email_reply_to }
+  let(:gitlab_subject_suffix) { Gitlab.config.gitlab.email_subject_suffix }
   let(:recipient) { create(:user, email: 'recipient@example.com') }
   let(:project) { create(:project) }
   let(:new_user_address) { 'newguy@example.com' }
@@ -31,6 +32,9 @@
     sender = subject.header[:from].addrs[0]
     expect(sender.display_name).to eq(gitlab_sender_display_name)
     expect(sender.address).to eq(gitlab_sender)
+    if gitlab_subject_suffix.length > 0
+      is_expected.to have_subject gitlab_subject_suffix
+    end
   end
 
   it 'has a Reply-To address' do