How to use an email layout with Devise

To use a custom email layout with Rails 5 and Devise, open config/initializers/devise.rb and add this line:

# Use layouts for Devise
Devise::Mailer.layout "mylayout"

Then, add a new file to app/views/layouts called mylayout.html.erb:

<!DOCTYPE html>
<%= yield %>

Of course, you can change mylayout in both the Devise config and filename if you’d like to call it something different.

Remember to restart your server before testing this.