Have you ever sent emails from staging to real customer?
Mailtrap -- Safe email delivery testing. Simply putting mailtrap.io/ as the default SMTP server in your application's configuration allows viewing all of the emails your application delivers without spamming your real customers. Easy to review email appearance as a real customer sees it and share it with your team.
Product by railsware.com
Here is a Lightning talk by Yaroslav Lazor. Railsberry 2012