diff --git a/CHANGELOG.md b/CHANGELOG.md
index aced36c46..306f90f81 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -11,6 +11,7 @@
 - Ability to disable invoices generation and interfaces
 - Added a known issue to the README (#152)
 - Ability to fully rebuild the projets index in ElasticSearch with rake fablab:es:build_projects_index
+- Ability to configure SMTP connection to use SMTP/TLS
 - Fix a bug: invoices with total = 0, are marked as paid on site even if paid by card
 - Fix a bug: after disabling a group, its associated plans are hidden from the interface
 - Fix a bug: in case of unexpected server error during stripe payment process, the confirm button is not unlocked
@@ -33,6 +34,7 @@
 - [TODO DEPLOY] add the `MAX_IMPORT_SIZE` environment variable (see [doc/environment.md](doc/environment.md) for configuration details)
 - [TODO DEPLOY] add `- ${PWD}/imports:/usr/src/app/imports` in the volumes list of your fabmanager service in [docker-compose.yml](docker/docker-compose.yml)
 - [TODO DEPLOY] add the `FABLAB_WITHOUT_INVOICES` environment variable (see [doc/environment.md](doc/environment.md) for configuration details)
+- [TODO DEPLOY] add the following environment variables: `SMTP_TLS`
 
 ## v4.1.1 2019 september 20
 
diff --git a/config/application.yml.default b/config/application.yml.default
index b8822ecd6..a79dc114c 100644
--- a/config/application.yml.default
+++ b/config/application.yml.default
@@ -36,6 +36,7 @@ SMTP_PASSWORD:
 SMTP_AUTHENTICATION: 'plain'
 SMTP_ENABLE_STARTTLS_AUTO: 'true'
 SMTP_OPENSSL_VERIFY_MODE: ''
+SMTP_TLS: 'false'
 
 # Google analytics
 GA_ID: ''
diff --git a/config/environments/production.rb b/config/environments/production.rb
index 46ccc5963..65d152210 100644
--- a/config/environments/production.rb
+++ b/config/environments/production.rb
@@ -104,6 +104,7 @@ Rails.application.configure do
     authentication: Rails.application.secrets.smtp_authentication,
     enable_starttls_auto: Rails.application.secrets.smtp_enable_starttls_auto,
     openssl_verify_mode: Rails.application.secrets.smtp_openssl_verify_mode,
+    tls: Rails.application.secrets.smtp_tls
   }
 
   # use :smtp for switch prod
diff --git a/config/environments/staging.rb b/config/environments/staging.rb
index dea7214d9..a18e94bee 100644
--- a/config/environments/staging.rb
+++ b/config/environments/staging.rb
@@ -106,6 +106,7 @@ Rails.application.configure do
     authentication: Rails.application.secrets.smtp_authentication,
     enable_starttls_auto: Rails.application.secrets.smtp_enable_starttls_auto,
     openssl_verify_mode: Rails.application.secrets.smtp_openssl_verify_mode,
+    tls: Rails.application.secrets.smtp_tls
   }
 
   # use :smtp for switch prod
diff --git a/doc/environment.md b/doc/environment.md
index da5af9f6b..91884c6bf 100644
--- a/doc/environment.md
+++ b/doc/environment.md
@@ -101,7 +101,7 @@ When sending notification mails, the platform will use this address to identify
 Configure the Rails' Action Mailer delivery method.
 See http://guides.rubyonrails.org/action_mailer_basics.html#action-mailer-configuration for more details.
 
-    DEFAULT_HOST, DEFAULT_PROTOCOL, SMTP_ADDRESS, SMTP_PORT, SMTP_USER_NAME, SMTP_PASSWORD, SMTP_AUTHENTICATION, SMTP_ENABLE_STARTTLS_AUTO & SMTP_OPENSSL_VERIFY_MODE
+    DEFAULT_HOST, DEFAULT_PROTOCOL, SMTP_ADDRESS, SMTP_PORT, SMTP_USER_NAME, SMTP_PASSWORD, SMTP_AUTHENTICATION, SMTP_ENABLE_STARTTLS_AUTO, SMTP_OPENSSL_VERIFY_MODE & SMTP_TLS
 
 When DELIVERY_METHOD is set to **smtp**, configure the SMTP server parameters.
 See https://guides.rubyonrails.org/action_mailer_basics.html#action-mailer-configuration for more details.
diff --git a/docker/env.example b/docker/env.example
index 40a8b4930..03f28b585 100644
--- a/docker/env.example
+++ b/docker/env.example
@@ -26,6 +26,7 @@ SMTP_PASSWORD=
 SMTP_AUTHENTICATION=plain
 SMTP_ENABLE_STARTTLS_AUTO=true
 SMTP_OPENSSL_VERIFY_MODE=
+SMTP_TLS=false
 
 GA_ID=