diff --git a/config/environments/production.rb b/config/environments/production.rb
index 7423852..a6ae03b 100644
--- a/config/environments/production.rb
+++ b/config/environments/production.rb
@@ -95,7 +95,7 @@ Rails.application.configure do
     user_name: ENV['SMTP_USER_NAME'],
     password: ENV['SMTP_PASSWORD'],
     authentication: ENV['SMTP_AUTHENTICATION'] || 'plain',
-    enable_starttls: ENV['SMTP_ENABLE_STARTTLS_AUTO'] || 'true'
+    enable_starttls_auto: ENV['SMTP_ENABLE_STARTTLS_AUTO'] || 'true'
     open_timeout: 5,
     read_timeout: 5
   }