app/mailers/application_mailer.rb
class ApplicationMailer < ActionMailer::Base
include ActionView::Helpers::TextHelper
include ActiveSupport::Benchmarkable
default_url_options[:host] = 'coderwall.com'
default_url_options[:only_path] = false
default from: '"Coderwall" <support@coderwall.com>'
ACTIVITY_SUBJECT_PREFIX = '[Coderwall]'
end