Mailgun
Mailgun is a tool for sending emails, primarily used by developers to enable their applications to send emails while avoiding common deliverability issues.
How to set up Mailgun for your Ghost blog
In this (hopefully short!) tutorial, I'll show you how to set up Mailgun on your Ghost blog. A number of Ghost features, including inviting authors, resetting passwords, and more recently, handling login for Ghost's Members functionality -- as detailed in our "Setting up a membership program for your Ghost blog"