ExpressMailer is intended to be a quick and easy way to send yourself or your team members nice looking emails about things that happen in your rails application. No need for creating a new Mailer, copy views, wade through email HTML, or any of that. Just tell ExpressMailer a few things about what you want to send, and it makes a pre-designed ActionMailer object you can manipulate or deliver. ExpressMailer is not intended to be a replacement for your user transactional emails (signups, notifications, etc). While there's nothing really stopping you from using it as such, it's probably never going to be flexible enough to satisfy all the needs of transactional emails. For user facing stuff, you should actually make something that's better and more personalized than ExpressMailer.