diff --git a/support/docker/production/config/custom-environment-variables.yaml b/support/docker/production/config/custom-environment-variables.yaml
index e157aaea9..831c6d1fb 100644
--- a/support/docker/production/config/custom-environment-variables.yaml
+++ b/support/docker/production/config/custom-environment-variables.yaml
@@ -33,6 +33,9 @@ smtp:
   tls:
     __name: "PEERTUBE_SMTP_TLS"
     __format: "json"
+  disable_starttls:
+    __name: "PEERTUBE_SMTP_DISABLE_STARTTLS"
+    __format: "json"
   from_address: "PEERTUBE_SMTP_FROM"
 
 admin: