Description:

Stubs out a new mailer and its views. Pass the mailer name, either
CamelCased or under_scored, and an optional list of emails as arguments.

This generates a mailer class in app/mailers and invokes your template
engine and test framework generators.

Example:

rails generate mailer Notifications signup forgot_password invoice

creates a Notifications mailer class, views, test, and fixtures:
    Mailer:     app/mailers/notifications.rb
    Views:      app/views/notifications/signup.erb [...]
    Test:       test/functional/notifications_test.rb
    Fixtures:   test/fixtures/notifications/signup [...]