diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index c82150503028a3fef4233ffac5ac5da7bd85b41a..8fd88f7b92e70d311694e850444795d61d4b73f8 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -5,6 +5,7 @@ variables:
   MYSQL_PASSWORD: studip_password
   MYSQL_HOST: mariadb
   DEMO_DATA: 1
+  MAIL_TRANSPORT: debug
 
 stages:
   - Checks
diff --git a/docker-compose-dev.yml b/docker-compose-dev.yml
index 0306f2cc9b87c8d69889e1753f5938f248e64416..f202a0717cbda9ffd843e4b0d34085bdc8dd79f2 100644
--- a/docker-compose-dev.yml
+++ b/docker-compose-dev.yml
@@ -12,6 +12,8 @@ services:
       MYSQL_DATABASE: studip_db
       MYSQL_USER: studip_user
       MYSQL_PASSWORD: studip_password
+      DEMO_DATA: 1
+      MAIL_TRANSPORT: debug
 
   web:
     build:
diff --git a/docker-compose.yml b/docker-compose.yml
index 82c4bc4870da9cb71db674bd45fc1cbbe57088af..d96342fed20cf65df58a43eaa6b3d235cc036ccf 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -11,7 +11,8 @@ services:
       MYSQL_DATABASE: studip_db
       MYSQL_USER: studip_user
       MYSQL_PASSWORD: studip_password
-
+      DEMO_DATA: 1
+      MAIL_TRANSPORT: debug
   web:
     build:
       context: .
diff --git a/docker/studip/config_local.php b/docker/studip/config_local.php
index df8187a9ddcc58ba24b4d781638e43ec5fae37be..4e77ed8e20187ff68b4e19c8fb0f01576adb3681 100644
--- a/docker/studip/config_local.php
+++ b/docker/studip/config_local.php
@@ -20,6 +20,7 @@ namespace {
     $DB_STUDIP_USER = getenv('MYSQL_USER');
     $DB_STUDIP_PASSWORD = getenv('MYSQL_PASSWORD');
     $DB_STUDIP_DATABASE = getenv('MYSQL_DATABASE');
+    $MAIL_TRANSPORT = getenv('MAIL_TRANSPORT');
 
     /*URL
     ----------------------------------------------------------------