Rails 4.1 introduced a new feature which allows you to preview emails via your browser. This functionality was initially developed by 37Signals as Mail View, and later built into into Rails.
Start by figuring out where to put your preview classes, as this is depending on
your test framework.
ActionMailer::Base.preview_path will tell you where
Rails will look. This is
spec/mailers/previews if you are using RSpec and
test/mailers/previews if you are using Rails’ built in testing framework. You
can change the default via
You can now create a preview class in your preview path to load any dependencies
the mails may have. An example for a
Notifier mailer would be:
The method should return a
Mail::Message object with all the required data
needed. In the example above, the last create user is provided to have some sane
default data when previewing the mail. You can also use fixtures or create
random models, anything goes.
With the preview class in place, you can now go to
/rails/mailers where you
should have a link to the email preview (if nothing shows up, try restarting the
That’s it. Now there is not excuse not to close your email client when working on your Rails apps.
I think this functionality is quite neat, and useful for designing and testing emails within the development workflow. Although this will get you most of the way, it’s still a good idea to test how the emails looks in various email clients. Litmus is a great tool that makes this task easier.