Warn rather than failing if there is no smtp sender address

config/initializers/devise.rb

@@ -6,7 +6,15 @@
 # four configuration values can also be set straight in your models.
 Devise.setup do |config|
   # Configure the e-mail address which will be shown in DeviseMailer.
-  config.mailer_sender = APP_CONFIG[:smtp_sender_address]
+  if APP_CONFIG[:smtp_sender_address]
+    config.mailer_sender = APP_CONFIG[:smtp_sender_address]
+  else
+    unless Rails.env == 'test'
+      Rails.logger.warn("No smtp sender address set, mail may fail.")
+      puts "WARNING: No smtp sender address set, mail may fail." 
+    end
+    config.mailer_sender = "please-change-me@config-initializers-devise.com" 
+  end
 
   # ==> ORM configuration
   # Load and configure the ORM. Supports :active_record (default), :mongoid